When I morph into seemingly any mob that can fly, I immediately get launched northwest, and can't move any other direction. Collision with blocks also becomes extremely jittery. Other mobs don't seem to break things.

Mod Ver: 1.2.5.changeling.2-1.12.2

Mobs tested: Frikinzi's Fauna Golden Eagle (which is invisible, FWIW), Ice and Fire Hippogryph.

Does this also happen with vanilla mobs?

Does it happen when only Changeling is installed?

I've been working my way through the mods in the pack to identify the culprit. I do need to do further testing, though ground based modded mobs don't have the issue. It does work in a minimal test with this mod and I&F (and dependencies). The pack has 430 mods, so it might take a bit.