Fairly new bass player here (been at it for around 3 years after playing primarily guitar for decades). In my experience it really depends how you like to slap. If you slap like Flea - down thumb, lots of bouncing and AGGRESSIVE - then yes, I could see it maybe getting in the way. However more recently I’m trying to slap with parallel thumb and through the string - like Scott Devine was teaching on his Bass Accelerator course (highly recommended if you want to work on that technique). I actually find the pickup cover HELPS me anchor my palm and use proper technique when slapping through the string. In effect, it gets my right hand at a better angle to use that technique.