And, some of us are starting to reach our limits due to being boxed up for 4 months. When you study a population, you want to be able to study representative samples of said population. Global conditions for humans are not even close to representative right now. Given the known effects of confinement stress on humans, getting representative population samples for most sorts of studies seems difficult, at best.

Sure, and some of the rats are probably fine too. But it still skews studies...