Cancel culture is a big problem everywhere on the internet, but unfortunately this isn’t something you can just “fix”. The best all of us can do, individually, is be more critical or who is getting canceled and what for. Try to talk to our friends about it and change how they act around the topic as well.
Things I always check before jumping at someone’s throat:
Am I sure this is real? Between image editing and deepfakes, it’s hard for me to trust anything anymore. I now trust the wayback machine, snopes and having several testimonies of the same allegation before anything.
When was the problematic thing done? Was it 5 years ago? That person might have changed and grown. How are they acting nowadays? Also, where they a teenager/kid? We all do very stupid shit at those ages.
Was the problematic thing something serious that damaged/hurt someone else in long-term? Was it something that pushes a specific and very damaging agenda? MAPs, Nazis, Fascists and similar are actually pretty recognizable, because there are a lot of groups out there dedicated to dismantling them and they have info on how to recognize the dog-whistles and recruitment techniques.
As I said, you can’t fix this at a large scale. You can, however, try to change how you react, and maybe some friends/family that are willing to hear you out.