Access to voting is the foundation of democracy. Sane systems try to minimize any “pressure” to not vote, for any reason, because any such pressure is very likely to hit some demographics harder than others. The Republicans in particular rather blatantly rely on weaponizing this as a way of subverting democratic principles, by making it disproportionately hard to vote if you’re working, or poor, or young, or a minority of pretty much any kind.
Therefore, anything that increases access to voting, and levels the playing field, is worse for the GOP than being able to keep up the status quo of voter suppression. Hence their extremely shrill opposition to mail, and also the (“hilarious”) claims of “fraud” - painting the picture of your democracy being subverted is a handy talking point while you’re busy subverting your democracy.
So the boring answer is that your question is sort of back-to-front: it’s not that the mail ballots are skewed as such, it’s that access to in-person voting is. Mail ballots favor the Democrats because it is their voter base that’s (in this case, anyway) being suppressed.
It’s probably natural - unless some big site like Reddit shits its pants yet again, there’s not going to be a major influx of new users. Even if something like that happens, parts of the fediverse are just a hard sell - relentless negativity, poor browsability and discoverability, trolling and bitchiness, and a lot of the content that’s left is just… dull.
I’m bored out of my mind too, and even then hanging here is only occasionally worth it.