I think I noticed more divergence in the level of preparation (although, didn't try to quantify it -- grad student here, limited responsibility/scope/ability to make change, so just informal observations). It makes sense -- with at-home instruction there's less of an opportunity to just passively check in with students, remote lectures are easier to ignore, and it is easier to cheat on tests when they are remote (so, unprepared students can get through more easily).
In particular -- it was a real struggle to get my first year college students to do any group work (an opportunity they'd usually jump at, because 50% responsibility, right?).
If this actually is the case, it is a really unfortunate outcome. I'm opposed to getting kids sick/exposing them to "mystery long-term health consequences." But setting them up for academic regression is also no good.
All in all, 0/10 pandemic, would not pandemic again. Not sure there could have been a positive outcome. Not sure what the least-bad option could have been. I wish we'd done more, though. I think we may have failed.
I wish we'd tried some really out there strategies. A pet idea I wanted to suggest was having the students on campus and organizing them by major into units -- so, your dorm/floor (depending on the size of the building) is all your-major students and it forms a unit. Call it the Harry Potter strategy. You can socialize normally with each other, maybe classrooms are assigned to a given unit. Maybe a grad student is assigned to (live with?) the unit (hard, though, grad students have their own lives going on and I guess they wouldn't want to restrict themselves enough to safely interact in person with the students -- I don't think I could). Lectures could be broadcast to the unit, with some local representative for the instructor. No interactions between units, but at least the students would have some peers to interact with. But I don't anyone would have been brave enough take responsibility for this sort of thing safety-wise (I certainly wouldn't), and I don't know that I'd trust the average school to work out all the details. But if it worked out, it could have been really something!
Actually, I guess we're far along enough to see if anywhere tried that out, and if so, if it worked out.