Flagging is for things that require moderator attention. "Very low quality" in that sense mostly means questions where we can't even tell what the OP is trying to ask, so we can't hope to answer.
For questions that are understandable but not the kind of question we handle, voting to close is the correct action. This includes opinion-based things (should I eat this food I know isn't completely safe) and various other things. If you don't have the reputation to vote to close, that's fine; others do, and things will get handled.
If you see a single user who's repeatedly posting questions that merit closure, feel free to flag one and we'll look at the pattern. (This isn't generally necessary since we get automatic flags if one user has a lot of closed questions, but it doesn't hurt.) But if you're just seeing a bunch of different users posting questions in a certain vein, there's nothing for us to do. We don't take action beyond what the individual posts merit. It's not one user's fault if a bunch of other users have previously posted similar questions.
With respect to the specifics you mention: I don't see a flood, and I don't see evidence of trolling. It's possible there are more naive safety questions than usual because so many people's lives have been disrupted by covid-19. But asking a naive question is not the same thing as trolling; please don't presume malice when inexperience is a possibility.