I think it's common mostly among the new-ish players, same as getting knocked out by own teammate who doesn't understand what team they're on (been there, done that).
One can only hope they learn with time and prioritize their targets in the future. I reckon some just don't care even though they realize what's up. Some will pick you out of spite if you had done something they considered unfair in their view.
Your best bet is to try and stay away from combat and solely hunt the winning team avoiding everybody else. Sometimes it means just chilling somewhere on the sides waiting until the opportunity presents itself, and honestly that isn't always fun. 🙃