For those on AT&T, June’s security update for the Samsung Galaxy S21, S21+, and S21 Ultra is starting to roll out today to users. We just received the update notification on our phones here. The build number should be G9***SQU4AUF5 or something to that equivalent depending on your model. This build should also include some other system updates that also fix some issue with overheating, although AT&T doesn’t provide a changelog.
If you haven’t received the update notification yet, you can check manually by going to settings > software update.