The recent question Why are usernames not unique? would also fit the tag usernames.

@MartinSleziak sure, I'd encourage you to create it (it doesn't look redundant with 'users')

There is also a minor question what name to use. (If it seems that creating this tag is a good idea.)

The corresponding tag is called user-names on Mathematics Meta: math.meta.stackexchange.com/questions/tagged/user-names , display-names on Meta Stack Exchange: meta.stackexchange.com/questions/tagged/display-names

But maybe choosing any of the three names does not make that much difference.

display-names is also the name on Meta Stack Overflow: meta.stackoverflow.com/questions/tagged/display-names

Of course, if you prefer, you could create the tag yourself. (Although I am not sure whether this tag has a chance to bring the taxonomist badge.)

I might have missed somethings, but it seems that you haven't created a tag on meta so far: data.stackexchange.com/meta.mathoverflow/query/1229812/… data.stackexchange.com/meta.mathoverflow/query/1229810/…

I see that I have mentioned the alternative names for this tag before:

Some examples of the questions where the new tag might fit: On the role of anonymity in a site dedicated to research-level mathematics, Using multiple accounts and pseudonyms, Celebrity usernames, MO policy regarding pseudonyms that are other people's real name. ...

... Recognizing identifiable users changing user names, Strange username, Why are usernames not unique?.

I only found one meta site where it is called usernames (without a hyphen) - namely English Language & Usage: english.meta.stackexchange.com/questions/tagged/usernames