I'm sorry you have been going thogh such a hard time, not just now in lockdown but in the past. I remember you talking with White Rose and others about the problems breaking up with a special freind.
Now you have reached the stage where you are physically and emotionally distanced from the group you associated with, and feel most reluctant to form new friendships as a result.
I get a very strong feeling you are a sensitive and thoughtful person and look upon relationships as serious, not a trait shared by everybody I'm afraid.
You mentioned more than once that others have said "you overthink it". I don't see it that way. I'd guess you are simply trying to understand how friendships work, and why they do not seem to last.
Being with a group at school is not really friendships -thogh sometimes they do form between individuals in the group. It is simply natural to gather together and do things together. If you are not actually present then I guess over time there will come a distance between you.
As a sensitive person the takes such matters seriously it hurts when your feelings and understanding are not returned in the same way. Be it by a group or individual.
I've found many acquaintances in my life, people who may have been daily "friends" in a workplace but when they or I leave that reduces down to be just a "season's greetings" card every year. They may be nice people but are in fact acquaintances.
Proper friendship is something else, it is deeper and lasts, and can be picked up seamlessly after gaps in time. If, like me, you are lucky, you will have maybe half a dozen in your life. The most important being your parents and a partner, if you are lucky enough to find one.
Don't get me wrong, acquaintances are a necessary and healthy part of life, and if one group falls by the wayside please seek another. It enriches you life and has the by-product of helping you cope with people. Plus it can be fun.
As Smallwolf asked, do you think you can find others who share your interests, and importantly what do you enjoy?