Perplexed...
 

Recently replaced my brake and backup lamps with aftermarket led bulbs. Very bright. However, now my turn signals hyper flash.
I didn’t replace the turn signal bulbs, and the hazard light still flash normally. Should I install an HD flasher (If available)?
2003 Buick LeSabre

LED lamps require a ballast . Some are self contained and some require an added ballast. Suggest you read up on this if you want to use them.

Leds do not play well with these cars. I put just a few in my interior and they blew out some lights in my hvac control! If you want leds, I'd use the least powerful ones!