Grounding Issue?

Well the thing I’d also like to add, is these bulbs have been in the car for over 4 years now with no issue. So this not working thing is fairly new
That statement means nothing. Don't allow yourself to be led down the wrong path by that kind of thinking. Something is wrong, because something has gone wrong. What have you tested to try and eliminate parts? AKA power to to and from the brake switch, have you checked the rear lamps for grounding, or maybe tried old style bulbs "just to see" or what?