I was playing in the proeminence modpack that has the mod, after a while tried putting the estrogen cookie inside the jar of cookies by right clicking, my game crashed, after i re-opened it and tried to enter the world, it starts loading and then the game closes again

Edit: Tested it again in a backup world, it happens the same when i try to use the normal cookie

Can you try updating Iris Flywheel compact mod to its newest version in the modpack?

Just encountered this error myself, updating like your suggested fixes the issue.

Update iris flywheel compat mod