Debris that's gotten into the controller is usually the main cause of it. Controller-drift can happen to many different types (Switches are notorious for it, but cleaning around the stick would be the first part. Get a toothbrush (one that you want to dedicate only to this), a q-tip, and some isopropyl alsohol (higher percentage is better). First tilt the control stick the opposite direction of where it's drifting and use the toothbrush to sweep away debris, you can do a full all-around-the stick clean this way too. Second, get the q-tip and dip it in the alcohol, doing a full-sweep around the stick to make sure there's no debris left. Let it sit and dry for a while before using it again.

If there is drift still afterwards, check to see if it needs to be calibrated. I don't know where the settings for that would be in the PS4, but sometimes you can see how badly it is drifting through that.

I'll try that thank you, I just dread taking it apart.
I'm sure I'll just have to get a new one eventually

Well, with that you don't have to take it apart, just cleaning the debris around the stick usually corrects it.

https://www.youtube.com/watch?v=POEXAmWJdYI
or
https://www.youtube.com/watch?v=7dVhU1dLmac

Hope this helps.

Oh nice thank you very much