We have a group chat on Teams at work for our whole department (we work from home still). Last week I was off work and then today I was reading through the chat and I saw that a colleague was calling out a perceived action of mine in a negative way. It was actually a management issue.
She obviously assumed that I would never have seen it. I approached her about it and asked her to not do that again she got extremely defensive saying - she doesn’t appreciate messages like that. Then I was told that she had gone to 2 other people in the team saying some “snake” had told me 
Aibu to think if she was genuinely aggrieved by something she thought I had done she could have spoken to me or a manager if she didn’t feel comfortable.
Calling someone out in a group chat to an entire team when that person isn’t there to defend themselves is bad and unprofessional behaviour?