Why is iPadOS 15 crashing all my games?

I use my iPad 6 almost exclusively for gaming. Not for full-on games, though; for mobile games. No FPSs, just side scrollers and puzzle games.

Of the 5 games I play almost every day, three almost never crash (maybe once every 6 months), once crashes with some updates every other day, and the other crashes at least twice a day -- I have to restart it before any important battle. The latter two games are almost certainly crashing because of memory leaks. I have noticed that they usually become slightly more stable immediately after an OS update, which I suspect has more to do with the hard shut-down than anything else.

That was until iPadOS 15. Now, all of my games are crashing periodically, often just while the game is on and I'm not doing anything. The game with the most, constant animation is also stuttering in its animation and touch input all the time. This game never used to crash at all!

What's more, these are not memory leak crashes (to desktop): this is the iPad resetting itself and requiring me to enter my PIN code! So it's almost certainly not the games, but rather the iPad/OS itself!

So what on Earth is going on? And what can I do to fix it?

To be clear, both the constant animation/input stuttering and the twice-a-day reset crashes are a major problem now.