The mini player model is very choppy, this is because InventoryScreen::renderEntityInInventory sets the partialTick parameter to 1.0F, instead of using the actual value for the current render tick.

Just duplicating the vanilla method and passing the current partialTick value is enough to make the player model render smoothly.

It's supposed to be like this, as this is also what it does in legacy console

And unfortunately, if I pass the current partialTick to a duplicate of the InventoryScreen::renderEntityInInventory method, this will need a workaround, because it needs to be changed certain rotations of the LocalPlayer, which causes a "jitter" in the model when rendering with the current partialTick in the EntityRenderDispatcher::render method