I saw a junior employee for the first time in a year or so last week (my company has been WFH throughout so we have only seen each other on Zoom and the like). The employee has worked hard in that time, but is just off a holiday. They looked terrible however - dark circles under eyes and very pale. I am their direct line manager and I am considering raising it with them. But they are not a very open person and I do not want to pry. Workwise, the employee seems the same, if a little disengaged (but part of that might be due to having a lighter workload now). I am just concerned about heading off a potential problem before it becomes a real problem.