I did this as well but I still get a very slight frame drop or two when I pull the notification shade all the way down. It seems to happen once I receive a new notification or if I pull it all the way down when it's being displayed over an app like Chrome. Otherwise setting it to high to always use 120hz has gotten rid of the scroll lag everywhere else. I'm on Unlocked US S21 Ultra variant running BUK7.I use Galaxy Max HZ, download them from XDA and set enable motion smoothness to HIGH. You will need to grant the app by ADB.
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