Bug Description

It seems that dev is missing some commits from 0.5.11:
7446c9c
ca89a54 (This mixin is present in 1.21/stable but removed from dev, did we drop it intentionally?)
19a25aa (Same as above, Mixin removed from multiloader)
3030f9b

I assume the first and fourth should be cherry picked, for the others we should confirm if we really meant to drop those features.

BillboardParticleMixin was renamed to SingleQuadParticleMixin, it looks like ca89a54 is already present in dev as part of ddecd77

OutlineVertexConsumerMixin was renamed to EntityOutlineGeneratorMixin, 19a25aa was included in the multiloader merge

I verified the other mentioned commits, and they appear to be applied correctly in /dev, so I'm going to close this.