The change to 100% rye was made before the 2001 tournament. The grass has been the same since then. Players began to get better defensively with each passing year leading us to believe that the courts have gotten slower with each passing year. In 2020 it appears to us as its playing slower than a mud court but it'll be the exact same grass as 2001.
I already posted in another similar thread the results I've got from a video frame-by-frame analysis comparing AO 2000 final (Agassi vs. Kafelnikov) and this year R16 match Djokovic vs. Wawrinka, which showed that the difference in deceleration by the surface between 2000 and 2013 is only marginal. But the players abilities and tactics have significantly improved by now.
Vote the biggest victims of Surface slowness