Minecraft v1.16.5
Forge v36.0.10
CTM v1.1.2.6

When a stained glass block using ctm is pushed by a piston, the game immediately crashes. Only this mod was installed.
Resourepack used: https://www.curseforge.com/minecraft/texture-packs/mc-connected-ctm
Crash Report

This was caused by a change in forge: MinecraftForge/MinecraftForge#7441

For now you can either use an older version or disable fabulous graphics. I'm working on figuring out the best fix.

Alright, thanks! I don't believe I was using fabulous graphics though.