See this clip from another resident for reference: https://i.gyazo.com/945bfcd536d5ba18e18795f64d159640.mp4

For vehicles in particular, if you alt-click on the root prim of it, while in motion, any child prim that is also moving (by transform or by llTargetOmega), avatars and nametags will follow the normal moving update path while the root will update faster. This is 100% reproducible.

This results in a "dislocation" and spasming of the links.

Digging through the history, it appears there were possibly some previous tentative fixes in llDrawable.cpp that broke doors and other things. (see MAINT-1742 MAINT-2247, MAINT-2275)

But it seems neither of those fixes just simply updated all the child prims along with the root as you would expect it to do.