Thanks Bruce and Frances. Yes, I checked all settings and admin activities - nothing relevant there. I am ABSOLUTELY certain, this has nothing to do with moderation settings. It happened in several groups, for two different emails (I'm webmaster of one association the group.io group is for, administrator of the other), none of them are moderated, no flags are set, no hashtags were applied.
I sent a message to support and we'll see what they say.
Carola
