Samsung rolls out another One UI 4 stable update for the Galaxy S21 to address lag issues

Samsung rolls out another One UI 4 stable update for the Galaxy S21 to address lag issues

It was just last week when Samsung started rolling out the first One UI 4 stable update for the Galaxy S21 series. The update bumped the devices to Android 12, introduced a plethora of new features, included Android security patches for November 2021, and even enabled eSIM support on the US carrier models. However, users who updated to this build reportedly faced some annoying lagging issues related to a buggy adaptive refresh rate implementation. Samsung is now rolling out another stable One UI 4 build for the Galaxy S21 lineup to address these bugs.

XDA Forums: Galaxy S21 || Galaxy S21 Plus || Galaxy S21 Ultra


According to a number of reports, the screen refresh rate in the original stable release of One UI 4 reverts from 120Hz to 60Hz as soon as the user’s finger stops touching the display. As a result of the anomaly, the UI elements, animations, and scrolling appear to be lagging. Interestingly, the bug mostly affects the Snapdragon 888-powered US variants of the Galaxy S21. After officially acknowledging the issue, Samsung has now come up with a hotfix update that replaces the previous release. The new build, which bumps the software version from G99xUSQU4BUK7 to G99xUSQU4BUK9 on the US carrier models, has started rolling out to users in an incremental fashion.

Samsung Galaxy S21 One UI 4 stable BUK9 OTA

Screenshot credit: Reddit user u/matthewreiter73

As of now, the new One UI 4 update is live on Verizon’s network. Other US carriers are expected to roll out the same in the coming days. Although the official changelog doesn’t specifically mention the 120Hz bug, the enhancement is rather noticeable, according to those who already installed the update. The scrolling lag on third-party apps is still not resolved properly, but the overall responsiveness of the phone seems to be improved a lot.

Apart from the US carrier models (U), the carrier unlocked (U1) Galaxy S21 units have also started receiving the stable One UI 4 update in the form of software version G99xU1UEU4BUK7. It could be possible that the aforementioned fix is already present in the unlocked variant’s update, but we have yet to spot its changelog to verify the hypothesis.

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Skanda Hazarika
Skanda Hazarika

DIY enthusiast (i.e. salvager of old PC parts). An avid user of Android since the Eclair days, Skanda also likes to follow the recent development trends in the world of single-board computing.

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