Thanks for all the replies guys, I had a friend take a video of me leaving with the car at dusk and in the video I was sent I can see the taillights are dim as well until I nail the gas then all the lights on the car get brighter, it acts like it’s charging and then not charging even tho there is no belt squealing or anything. This alternator was brand new in summer of 2019 so I’m hoping it’s not bad yet.
I would suggest using a DVM to check the alternators output vs what the battery is getting wit the lights on and off at ~ 2500 RPM or so. Ideally the readings should be within .2 to.5 V and about ~ 13.8 to 14.5 and steady depending on the age of the harness etc. If they are jumping around you now know why the lights are doing the same. IF not, you've eliminated the charging system and can start looking elsewhere
