[EC900]

I’ve seen this sort of problem on domestic cars. Im not electrically savvy but error prone as the next novice in that department. I once swapped a 1157 for dead 1156 on a motorcycle trip to be compliant legal in an not-so-friendly out of state road trip, forgot about swapping back when I noticed the mishap in functionality.

Are they all the proper bulbs… #1034 originals spec or the universal dual filament 1157 ? Not that 1157 won’t work, it might be an 1156 single filament used as a quick replacement at some point.
The bulb (posts) can only be inserted one way, wrong bulb/wrong socket, maybe the the previous owner put the left bulb in wrong orientation and not making proper contact drawing voltage/watts and imbalance to other filament or right side circuit So look closely at the socket itself for damage.
Check and clean wiring, contacts and for grounding faults too.

I can’t say if the Brake dash warning light will detect brake wiring faults but it is wired to the brake circuitry, (including the handbrake, that switch itself is difficult to set and get the dash light to shut off, I unplugged mine) check the wiring on the master cylinder brake light switches terminal connections.