jit-lock-function giving “invalid-regexp “Unmatched ( or \\(“” error

I am using emacs 30.1 on macOS 15.6 and I keep getting this error:

Error during redisplay: (jit-lock-function 5605) signaled (invalid-regexp "Unmatched ( or \\(")

Lots of things seem to trigger it; saving a file, doing occur, and I think some things related to auto-revert or even just typing. So there’s something related to fontification,

I’ve tried with --debug-init and I don’t see anything; I disabled any kind of font-related configuration and I still see the error.

I’ve seen this in various modes, so it doesn’t seem to be related to a specific mode.

Any ideas? Where is that bad regexp?