A blown fuse is always a sign of excessive current flow. In this case, it's probably caused by a short circuit in the brake light wiring.
You need to check the wiring for power to the bulbs.
fuse, bulbs
Check the bulbs, fuse & brake light switch on the pedal.
Wiring or bad bulbs
A short in the brake light circuit.
A defective or out of adjustment brake light switch.
It can be connection wires, bulbs or fuses.
Friend says cause your brake light is out., although im not sure that i can trust him.
Your brake booster is malfunctioning
Probably the wrong bulbs or the brake lights are getting stuck "on". Or maybe a combination of the two. Check that you have the right bulbs and check to make sure something isn't keeping the brake lights on. FriPilot
normal wear and tear. Brake light switch, bulbs or sockets.
Check the bulbs, then the fuse, then the switch at the pedal.