My car since the day I got it ( 14 months ago ) the headlights over time have progressively started to flicker worse and now even my brake lights and interior lights I can see flicker..
I never had a dead battery or low voltage issues but could it still be a janky alternator ? Do these have ground strap corrosion issues that I need to check for ?
I'm 100% my belt isn't slipping...

 

Anybody????

 

From your description, you have a single point of failure somewhere. You might start with the light switch & associated plugs.
Certainly, the battery connections & ground straps are common MINI failure points & easy to clean.
Then I think I'd look at the relays & fuse box connections.

 

Did you already measure the battery voltage when the car is off and during driving?

 

Please tell us what it was if your figure it out.

Thanks,
Peter