a couple of times in my career I've had a change of manager. Eg old team there was 2 team leaders. One day I was told the other one was my team leader, can't remember if it was verbally or via email. The team leader didn't do much - I never had 121s, they weren't involved in anything.
Another time it would be our managers manager changed. Again there was no formal "this is he new structure" we were told. They even travelled the four hours to the office, there was no "this is the new structure" or any talk.
Aibu? Usually if there has been a structure change and t doesn't affect your job, you still have to be told formally?