I literally came to ask a similar question as I have done a side by side comparison with the original 2011 Blu ray and the dremasters.
Granted I am watching the dremaster on my 1080p phone (not sure if the phone is automatically downscaling it from 4k to 1080p through the google photos app?) but I did definitely notice less grain in the dremaster compared to 2011 Blu ray remaster.
I have also played the file on my 1080p tv and noticed the same reduction in grain.
I understand the original notes for the dremaster say it will “cleanup” the grain but I would be curious to have the 1080p edition before the upscaling process to 4k. 🤷
Also, my guess is that, maybe the Dremasters weren’t trying to remove the grain, but to mitigate any digital noise in the footage. It can be easy for people to confuse digital noise for grain sometimes.