Yeah, I can appreciate this frustration. I think it’s perfectly acceptable to want a relatively smooth, timed run, and not have to play fight for survival because of someone that’s brought in drastically undergeared.
That kinda group should list up front that they’re bringing an undergeared friend, so folks know what they’re getting into.
I would start here. I think this is a safe bet that if you left just that one, you’ve got 0 issues. If you’ve left, maybe half a dozen like that for the season, i would still argue that you wouldn’t get actioned.
You’re right: we don’t have any definitive, 100% empirical threshold on what constitutes ‘transgression,’ but that’s because - I think - there’s human factors involved, and nuance. I would say that try not to leave more groups than you join, and don’t respond to any whispers from players that were in the key you - the royal you, the editorial you - left.