Blinker issue in 2003 tacoma (prerunner)

https://www.youtube.com/watch?v=6AFeTkGd5Kw (left turn signal does this sometimes when pedal is pushed down)
Hello! i am here again with another issue. The truck has been doing this sometimes (sometimes it works sometimes it doesn't) for the past ~3k miles and we don't know what the issue is... anyone here have the same sort of problem? This only happens once the brake pedal is pushed down and we have no idea what it is. Any idea would be appreciated! thanks!

 

You have an 03 which I believe is post-when they started checking the resistance of the light circuits to make sure the bulb wasn't dead. What type of bulbs are you running?