I had an idea for a quick and easy mod for Minecraft Forge, but not being much of a modder, I can't do much with the idea. Instead, I'm posting it on the forum to see what you guys think:
Fall Damage Debuff.
Basically, the more fall damage you receive, the worse the debuff will be. The idea is that it will simulate a sprained or twisted ankle, so the debuff could be something as simple as having the effect of Slowness I/II/III (or however high it goes) for a short period of time after landing.
I'm currently running a modded 1.16.5 personal server that I'd like to add this onto.
Let me know if you're interested in making the mod. Thanks!