I'm assuming that the employee in question is using company eqipment while WFH and you were sniffing around a bit? I'd be frank with them to stop that behaviour and give them a warning..

No, they are fully remote but have a public leetcode profile, which shows recent activity "x minutes ago", for example. @iLuvLogix

Were the leetcode problems related to what they are currently working on?

@iLuvLogix Not in the slightest

Then give them a warning in wiritng (e-mai) and demand that they stop that behaviour - though it might result in them using a different profile that can't be assiociated with them ;)

Are you sure it is the same person. People do have the same name. Also, my husband uses some of my accounts.

Have you also considered that he might be working on leetcode during "work hours" but them finishing tasks in his personal time?

do you know that he clocks/bills the time he is spending on leetcode? A buddy of mine often works 10h will only clocking 8 because he spends so much time on sites not related to work in the slightest.

Can you clarify whether this is a full time employee with an employment contract or a contractor? Also, is the work expected to be done during specific hours?

As transpired from comments, the question would benefit from a further detail on the actual performance. In particular, how often the developer is missing deadlines, what explanations was offered when challenged, what is the additional context to that? A thing worth considering, is that activities such as reading or solving abstract problems are correlated with immense productivity gains. I encourage my developers to pursue creative learnings as that makes them better at work when they learn how to use more efficient tools and think creatively.

In my experience it's not uncommon that software developers don't work 8 hours a day. Plenty developers browse stackoverflow "for fun", or even watch youtube videos or visit facebook, and some even play games. Admittedly they often (try to) hide it from their boss. Some people can get more done in 2 hours than in a full day if they can do more relaxing things in between. You should ask yourself what you are willing to spend on the product instead of thinking whether the developer is actively working all the time.

Did you notice this while you were on Leetcode during work hours?

Regarding A C’s comment, it actually would be useful for you to explain how you know they’re spending so much time on leetcode, especially since you’re only estimating that it’s 2 hours a day. You could end up looking foolish (at best) if you confront them on this and either your time estimate is wildly exaggerated or this person on leetcode isn’t your employee.

What was your interview process? In particular, did you ask coding questions similar to Leetcode?

Obligatory xkcd (303).

There is a possibility that this employee is getting ready to leave. Doing Leetcode puzzles may be a way to prepare for their interviews.