[Fixed Links] Need help with Entity jitter when rotating. 1.21.8

[YTNR]

Currently trying to write my first Entity with a custom Renderer, I even have it working, but its got a few small glitches i need help with.
### Goals:

1. The entity is supposed to be able to look like any Block, similar to falling Blocks.
2. I want to be able to scale, rotate and move it in any way.
3. It needs an anchor function, which can take a location or entity and stay at an offset to it at all times. This should be very accurate, I don't want it to lag behind the Player.

### Problems

1. I just can't get the rotation to be smooth. When i start rotating it at constant speed, it jitters very slightly and doesn't seem like the normal entity movement in minecraft.

2. Very similar to 1. the anchoring seems to be lagging behind at best, it jumps a lot and sometimes might even not move properly

### What I've tried
I think there might be some interpolation problem going on, I just can't quite put my finger on where it happens. I've tried interpolating at different places and it all still stays jittery. I've tried looking into how minecraft handles Players riding entities etc., but i couldn't quite figure out where that is handled. I feel like my code isn't clean for some reason, clean meaning, that im just to unsure about what i have to do and don't, what is already integrated or not etc. Im pretty new to Neoforge, though i've done the basics and read through the docs. still no solution. I've thought maybe I'll do the rotation on the client side only, as i don't need it on the server.

Alternatively i might have some problems because im reaching across sides some way, or things run on both sides, that are just supposed to be on one. I've looked everywhere I could, but can't find anything, i'd deeply appreciate if you could take a look at the two files.
ShapeBlockEntity.java

ShapeBlockRenderer.java