Question UnityPerMaterial CBuffer inconsistent size inside a SubShader

This error happens because the shader you are using is not compatible with the SRP Batcher. The most likely reason is that there are #ifdefs in the UnityPerMaterial constant buffer definition, which causes that constant buffer to be different for different variants of the shader, which is not supported when using the SRP Batcher. Entities Graphics relies on the SRP Batcher to render, so all shaders used with it must be SRP Batcher compatible.

The reason why this only happens in the player and not the editor is that the editor compiles shader variants on demand, based on what is used, and the player build compiles all variants up front.

The way to fix this problem is to fix the shader so it's SRP Batcher compatible. In these kinds of cases, it's usually not difficult and typically just removing the #ifdefs is enough.