Second February update seemingly addresses Samsung Galaxy S21 battery drain issue
The changelog isn't all that descriptive, and like the update that came before it, it talks about improvements in overall performance, security, and camera. Although Samsung doesn't say so explicitly, it appears that the update seeks to address power consumption issues that were caused by a recent update as some users on XDA Forums say that it has fixed those problems.
According to posts on Reddit and Samsung’s Community forums, the previous firmware update affected battery life substantially. Apparently, this was only a problem for Exynos-powered Galaxy S21 and S21 Plus. Users had reported that putting the phone on Airplane mode fixed the issue, which implies it had something to do with cellular connectivity.
The new update is currently being rolled out to users in the UK, Switzerland, Belgium, and Germany, and it will likely reach more markets in the coming days. You can also check for it manually by navigating to Software update in Settings and tapping Download and install.