I think one of the kindest things you can do for people with various mental health struggles is just... let people back into your life after they've been absent for a while.
Making friends as an adult is so fucking hard already and isolating yourself from other people is a very common symptom of depression, anxiety, burnout, ocd, trauma, grief, etc. Which means that someone will do the hard work of recovery/healing and resurface back into a world where their previous friends have written them off because they stopped showing up.
So if you know someone where you're like "yeah we could have been better friends but they fell off the map a bit" and that person suddenly reaches out, or starts showing up to events even though you kind of forgot they were still in the group chat... well they may have been Going Through It and you don't actually have to punish them for their absence you can just be glad that they're back.