Potential service return nerf which accommodates different skill levels:
Reduce the arm reach on return for regular returns (accel, normal) but increase it for slice returns. That way if you really don’t wanna be aced, slice
+ the depth on the slice return should be high so it’s not instant winner, i.e. sails deep to the baseline. Can only hit a good deep regular return if you cheat over to that side or anticipate it early, less so if you react.
High skill level returners would hit less slice returns and lower skill returners would hit more slice returns but not with a high penalty of the next shot being an easy winner.