The bathroom lights work, but once in awhile they will go out and not come back on for awhile. This happened a few time in the last month.

Is it an older fluorescent light fixture?

Are they recessed cans with high wattage bulbs? Are they regular bulbs(incandesent), Multiple bulbs in 1 fixture.
I would change the switch, quick and cheap if you have no meter, if it continues, it is likely not the switch, then Fixture connections would be next.
Bulb sockets can fail.
Usually if you remove the bulb and look closely at the rivits inside the socket for burnt/black where rivit connects to socket connection. Burnt will cause intermiddent connection.

Are they recessed cans with high wattage bulbs? Are they regular bulbs(incandesent), Multiple bulbs in 1 fixture.
I would change the switch, quick and cheap if you have no meter, if it continues, it is likely not the switch, then Fixture connections would be next.
Bulb sockets can fail.
Usually if you remove the bulb and look closely at the rivits inside the socket for burnt/black where rivit connects to socket connection. Burnt will cause intermiddent connection.

The bathroom was completely gutted out and everything replaced around 5 years ago

Are the bulbs too high a wattage and opening thermal?