Mine was doing this in my 2018 SL. I have a theory.

Do you drain/fill your ballast and use your boat a lot? I think as the ballast pump impellers get worn out, the filling is fine, but the draining is not as efficient. Maybe it has to do with the force it takes to push water out below the boat vs the water pushing itself in.

The owner's manual says 100 hours and replace the ballast impellers. I'd have to agree with that. Mine were rock solid accurate based on timers until i got to about 80 hours. Then it started not wanting to drain that well.