I can’t say with certainty but I found a neutral wire removed from an AFCI and sandwiched between the dead front and the box. Clearly it didn’t just “jump” in there. House was a foreclosure with all appliances missing (even the light bulbs)
If you disconnect the neutral on a GFCI or AFCI breaker & relocate the neutral from them back to the neutral bus they will function as a circuit breaker only w/ none of that pesky tripping.:( Which looks like what someone did there…