Although Samsung has officially begun distributing One UI 4 to Galaxy S21 users, there are reports of some users experiencing lags. Despite offering multiple beta builds, some issues continue to plague users. Multiple reports indicate that Samsung started rolling out the Android 12 update on top of One UI 4.0 to its Galaxy S21 series globally earlier this week. Users seem to be experiencing no issue with the update, but users from the United States have complained about the UI stutter after installing it.
One UI 4 appears to be experiencing lag due to a bug that most likely results from the high refresh rate option on the display. When that occurs, it switches from 120Hz back to 60Hz as it should not. Samsung Galaxy S21 displays are capable of adaptive refresh rates. This allows them to adjust their refresh rate according to the content and user input on the screen.
But after an update to Android 12, the screen automatically reverts to a 60Hz refresh rate as soon as the display no longer detects any touch input. This happens regardless of whether animations are displayed. Consequently, the affected users experience a lot of frustration due to this unwanted behavior that causes scrolling to stutter. The problem seems to be affecting mostly the USA variants of the Galaxy S21 series.
Fortunately, if you have the international Galaxy S21 series, then you shouldn’t experience any lag at all. Most likely, Samsung will fix this issue with its upcoming software update. That may take a while.