Nowadays, I really don't care much about the mud but Bull's game in 2018-19 off clay has been much more exciting to watch. More Aggressive. Less Grinding.
This is bit of a misconception. Nadal especially while he's having a good day is actually very aggressive on clay, much more so than he's on a hard court. He often aims for the corners, or extreme angles, and is very accurate; any "grinding" is partly the surface's doing. his opponents can still get to the shots, but end up scrambling. The best example (even if it's an old one) to this is RG 2008 - not the final in particular, the whole tournament where his forehand is often similar to an unreturnable fast-paced kick serve. Another can be RG 2014 - in the final after the 1st set he started to smack his forehand as soon as he can which resulted in a shower of winners. On a hard court, even when he's having a good day. he has a tendency to fall back and really grind his way to win a point. I think that makes him (subjectively of course) much more tedious to watch off clay (the snail pace between serves and points does not help), while on a clay court match he'll often not mess around, plus firing some ridiculous winners.
With that said I used to watch his matches on clay often, nowadays not that much but that's my overall interest level going down.
Edit: I realized after posting that you refer to 2018-19 specifically and not his whole career, but for the most part I would stand by what I said.
