I'm having frecuent crashes, I'll leave the crash reports here:

crash-2025-05-05_10.05.13-server.txt
crash-2025-05-05_10.57.56-server.txt
crash-2025-05-05_15.17.24-server.txt
crash-2025-05-07_11.09.20-server.txt
crash-2025-05-07_11.45.06-server.txt
crash-2025-05-03_20.13.18-server.txt

I have a Similar problem on my own server. Trying to put mixin.shapes=false in Lithium config is not successful, because cast cannot happen even with vanilla variant (class net.minecraft.world.phys.shapes.CubeVoxelShape). I think this is a problem specifically with IntegratedDynamics mod, and the modpack uses an older version of it (older 1.24.1 vs 1.26.0).

Tried updating the mod to 1.26.0 and got the same problem multiple times, honestly this makes the modpack quite unplayable. I have like 2 minutes to enter the world and do stuff until the entire world crashes.

I'll start an issue in the IntegratedDynamics mod github, maybe that will be more helpful

Continue in CyclopsMC/IntegratedDynamics#1509