I can’t guess your specific issue other than maybe the wires for the light and the speakers are in close proximity, or the switch is close to the radio and electrical interference is playing a role.
Years ago we had a touch lamp at home. For months we would argue over who left the light on, with each of us swearing we had left it off. We would come home from being out and the light would be on. Then one night we were sitting there and the phone rang and the light came on low with the first ring.......the second ring it went to medium, the third ring went to high, and the fourth ring went to off. If it rang again, it would be on again.
Rob & Amy
2019 Passport 240BH SL
2015 Ford F150 3.5L Ecoboost SCrew 4x4 w/Max Tow Pkg