Several times I was noticed that I was deleted as collaborator from different tasks and none of others hasn’t deleted me. I don’t know the reason, can somebody help me, may be it’s a bug?
I’ve never noticed that.
I would suggest looking closely into whatever was happening in those tasks, projects, or teams at the time, and see if there is a clue. Maybe a project was added to a Team that you don’t belong to, and then deleted from the Team that you do belong to? (I have’t tested it, just a possibility.)