@Taco_lad
It is in dev mode, but the sensors are not disabled.
(It's probably a moot point whether it's better to say "not disabled" or "enabled", but the button is literally labelled "Sensors Off" and the button is off, aka "sensors off is off", hence "not disabled".)

Generally the only thing I touch in the dev options is visible taps, though it's certainly possible that I accidentally touched something else. However, I don't believe I visited the dev settings during the time that the camera stopped working.

Furthermore, if I enable the Sensors Off button (aka disable the sensors), I don't regain flashlight functionality.

Nonetheless, it's more advice than I had before, and none of the help docs or troubleshooting pages recommended checking dev mode (which I almost always enable on my devices), so thanks for the thought!