We also don't do "homebrew (or in this case houserule) this for me" type questions so I'm not 100% sure that the question in its current form is something that can be suitably answered on this site. I could be wrong and I am about to head to bed but I will leave my close vote for now, let other members of the community cast their votes and we'll see where things go from there.

How high a level is your party and how many temp HP does this actually give them? Are you finding this is unbalancing combat too much? Making encounters too easy?

@PurpleMonkey: There is a homebrew tag that has quite a lot of questions that are not closed and do have upvotes and answers. So I don't think homebrew is not answered here by default. It's also not mentioned in the "what questions can I (not) ask here". That being said, this is not a homebrew question, let a lone a "homebrew this for me" request. It is a question on how this feat is supposed to be used in a game, or how it is used in general. "Techniques for running or playing RPGs; " is on topic according to the Help, and I think that is exactly what this question asks for.

@PJRZ: They are level 6, and the Roque has +2 CHAR. So it gives them all a +8 HP boost. That's about 20% considering their HP's, which is quite substantial. It's indeed a significant factor in combat encounters. For me it wasn't really a problem (yet) because I take it into account when creating combat encounters, but my players said they didn't like the ruling that the +8 should just be a permanent extra HP. And I kinda agree with that, I just don't know how to correct it without nerfing the feat.

Just to check - are you increasing their max HP or assuming the temp HP gets assigned every short rest? Because temp HP acts quite differently from real HP and it'll get a lot more powerful if you actually increase their max HP.

"my players said" does this include the rogue who took this feat?

They get 8 Temporary HP every rest, but as per the rules: they always lose the previous source of temporary HP (so it doesn't stack). So a character with 40 base HP always has 40+8HP in total after every long rest. It is noted in the separate field on their character sheet, so it's clear they can not regain the temporary HP by any means of healing.

Can you define the problem a little more clearly? Is it that both you and the players think the feat is overpowered at your table, but you want to keep it and do something that makes it more reasonable? What specifically do they think is problematic?

@Caleth: Good question. He was there when the discussion was happening, and also was present when we discussed the matter with only two of the players after the session. He did appear to also feel like the Feat in its current form isn't really like it's supposed to be; but he was strongly opposed to create a rule where he had to give a speech every morning in order to get its benefits.

@NautArch: Maybe Overpowered isn't necessarily the problem (but it might be). The main issue is that we think it feels wrong that this source of temporary HP now de facto becomes a permanent 20% HP boost for everyone. That feels like we're not using the feat right, even though RAW we do.

@NautArch it hasn't impacted combat because I always scale my encounters to what I think the players can handle, and how it should wear down their resources. If I wouldn't have done this, it would definitely have made them significantly stronger. A lot stronger. This isn't a problem per sé. It's just that it feels like we're doing something wrong here. It doesn't feel natural that a feat should give a full party a +20% HP boost permanently. This is mainly how my players feel about this, but I can understand why they do.

@Opifex Do you add +1 AC to every enemy whenever someone takes an ASI in their combat stat? Making combats stronger when someone takes a feat like this is slyly invalidating their choice and taking away their agency. Regardless of how OP you may feel the player made a choice based on how the game was, so changing the game to invalidate that (by making combat harder) is bad form in my eyes.

@SeriousBri I don't make the combat harder based on the choices my players make. I simply make encounters that my players will find challenging enough and not boring. For example, the current party has great synergy and beats encounters that should be TPK for most other parties. Encounters as written would become boring very fast for them, so I scale them up a bit. If I would notice that encounters would become too hard, I would do the opposite. I don't see how this is bad form. I think every DM should do this. Also: don't forget that it's primary the PLAYERS who asked to rethink this feat.

@Opifex it's not that homebrew isn't answered here by default or isn't an acceptable answer to a question, it well and truely is and we even do homebrew reviews, it's just that we don't handle question asking us to create the homebrew. See How do we ask for homebrew suggestions? and 'Homebrew a class for me' questions.

"How should I rule Inspiring Leader" appears to be asking us to create a houserule for you and as SevenSidedDie answers "“Give me your experience with homebrew armour rules” is not a question that would survive on the main site. It's a poll...". As NautArch stated we need to know that actual problem and the question needs to ask about that problem.

@PurpleMonkey 1) the meta post you refer to talks about suggestions on how to use a homebrew armor. This question asks about how I should use a non-homebrew feature of 5e. 2) The same posts says "Instead, ask about your problem, and ask it to be solved.". That's exactly what I did here. I described the problem and asked how it should be solved. I never mentioned anything homebrew or houserules. 3) further it says "Once asked, however, answers will have to be from experience.". This is exactly what I was hoping for, and is also what the answers so far have given.

@Opifex You might have better luck getting this reopened if you remove references to "nerfing" and instead rephrase the last 3 paragraphs of your question to focus on the last sentence of the answer you rejected to that other question. Namely, when won't the party just automatically gain the HP after a rest. Both existing answers would still be valid. Caleth's would be along the lines of a frame challenge that it is fine, and my answer would provide some reasons when they wouldn't automatically get (or want to get) the HP. Then maybe some new answers can provide more situations like that.

@Opifex I believe I understand the intent of your question, and was similarly confused when I was accused of suggesting nerfing the feat in my answer, and asked to provide support for the nerf. I don't see my answer at ALL as a nerf, but it appears to be a common conception that many of those who voted to close your question think you are looking for. So, removing the word "nerf" should hopefully help remedy the confusion in what you are asking.

@WillemRenzema The reopen vote isn't mine. I haven't voted to reopen it because my intention is not to change the question. The way I read the rules of this SE, the FAQ, the tags and also the meta-post posted above, this question was perfectly fine the way it was written. I explicitly wrote I did not want to nerf the feat with some homebrew. Since the question is on-topic according to the rules, I don't think changing it will fix it.

@WillemRenzema: About your answer: I was also confused about the discussion that arose in the comments below it. I found your answer very useful and will think about the points your brought up before my next session. I did give you an upvote already, but usually before accepting an answer I wait a few days to encourage others to give other answers. However... since the question is closed others can't post any answers anymore. So I'm a bit torn on what to do here...

@Opifex The reopen vote is mine. The only reason I suggested rewriting was because I think people are getting hung up on the word "nerf", interpreting that as "homebrew", and then making comments to that effect, reinforcing each other's misunderstanding. I'm not suggesting a big rewrite, just remove the word "nerf" to make it a little more clear that you want a rules grounded answer as to why this feat isn't an automatic/permanent HP boost.

@WillemRenzema I edited the question with extra emphasis on the fact that I'm not looking for ways to nerf it, instead of removing them. Because by doing this I think I make it even more clear than I would by simply removing the words. However... I do feel the spirit of the question has changed slightly by doing this. (I also cast a vote to reopen)

Let us continue this discussion in chat.

This might be a good question, for a bit of brainstorming, to ask on a forum.