Someone else reported the same issue, Blender E-Cycles crashes as soon as you apply Grungit, and it looks like it’s from E-Cycles end for now.
From the Gumroad page of E-Cycles:
Known Limitations of the RTX version:
Raytracing nodes (Bevel and AO)
Grungit uses the Bevel, AO and baking only when you apply it for the first time. Once it’s done and the texture is generated, you can use models that have Grungit applied with E-Cycles without any issue.
I recommend opening the model in official/daily blender Builds, apply Grungit, then bring the model back to your scene in E-Cycels
There is a similar limitation with OptiX in the official builds where it throws an error if you use AO, Bevel or try to bake. I made a workaround that switches temporarily to CUDA and then back to OptiX once it’s done. However I am not sure it’s possible to do that with E-Cycles, I presume the backend is changed so much. I don’t have a copy and cannot test it myself.