Bug Cloth Constraints changed after upgrading from Unity 2018 to 2021

We have a project that was upgraded from Unity 2018 to 2021 LTS. I noticed a weird thing: Some of our prefabs have cloth components, and the Cloth Constraints change just by upgrading Unity. Here's two pictures to better explain what I mean.






Now to fix this, I could manually go over 100+ prefabs and re-paint everything, except that doesn't work either because I can't paint new constraints. Seems there are several threads on that specific bug about not being able to paint cloth constraints.

Anyone had this issue? Is there something I can do apart from trying to repaint all cloth constraints?

 

Actually here's the prefab if anyone wants to have a look. Texture references will be missing but you should be able to see the cloth constraints.

 

I found this thread that among other things discussed the same issue: https://forum.unity.com/threads/major-cloth-issues-in-v2019-2-0f1.730385/

Some slight progress, I learned that by setting the Optimize Mesh setting to Vertex Order, the cloth constraints are more accurate, but still not identical. Looks like a repaint is necessary anyway.