Interesting to see this going around on Twitter right now, because this
just happened to me:
A former friend/colleague of mine who unfriended and blocked me
years ago decided to temporarily unblock me to tell me, among other things, that I'm racist against Italians because I insulted her Italian heritage, and I have absolutely no clue what she's even talking about, plus she never bothered to point out what I even said or did that she perceived to be me insulting her Italian heritage - and I can't even further inquire for clarification, because she immediately blocked me again right after DMing to tell me off.
So, obviously, her actions and behavior clearly indicates that she cared nothing for trying to preserve a friendship, so if that's the way she feels, then there's nothing I can do to try to make amends for something I may have said or did that she, evidently, found racist and offensive.