It started as a joke on 4 Chan in 2017 get people to think the ok sign was used by white supremacists. The media naturally fell for it/ran with it as it creates a narrative of secret sleeper clan members waiting to strike. Mostly morons believed it to be true which included white supremists groups who now have adopted it.

I think a lot of this is about context too. I don’t think anyone would bat an eye if you used the ok symbol in that context. I still use it pretty regularly, but I’m also not a white dude or using it for no reason in photos and only to my white friends. They probably had some other problematic instances and this was the final straw to kick this guy out.