GSP is correct about the neutral. Had this happen in our house. Drove me nuts trying to find it. Our house was wired by the homeowner who built it (that we bought it from). And yes, I believe he was on crack. We've been here 25 years And I am still discovering oddities.
Youngest bought a house in south west Texas.
Called me and asked if I'd wire 8n some can lights. There were some dark spots in the master bathroom that needed some light.
Not only that, the sink light wasn't centered over the lavatory!
Sure! Be right there!
Kid had already bought some small remodel lights, si this should be easy peasy!
Installed and wired the lights. Wire to the switch and we're good to go!

Not hardly!
Had black wires and white wires tied to two different switches!
WHAAA....?
Finally went to the panel to try and figure out what's what!
There were black and white wires tied to the ground bar, white and black wires tied to breakers and ground wires tied to the ground bar and neutral bar! EVERY wire I tested with my Wiggy was hot! Even 2 neutrals!
What should have taken an hour max, turned into an 8 hour day!
Pulled the lavatory light.
There were white wires tied to black wires and vice versa!

Instead of moving the vanity light, we bought a new vanity top and installed the sink square under the light!
How in hell that house passed an inspection to sell is still a mystery to me!?