This is a very much a thing. Older audience members (👋) often don't intervene because, well, we've already checked out, or doubt that our intervention would help. Sometimes that's wrong, and is anyway no excuse. That said, if you do intervene though I did not, know at least that I have your back.
Devinone thing I’ll note on this is that as a young grad student it can be pretty disheartening to see a talk you’re pretty sure is bs but no one in the q&a is calling it out, and now you’re wondering if there’s something you aren’t getting