Battle.net app makes some file updates to files on your Win11 file system. This means that with UC set to anything above “Notify me only when apps try to make changes to my computer (do not dim my desktop)” in the User Account Control Settings applet you will get this notification and have to click “Yes” to allow it. The easiest solution is to open User Account Control Settings applet and change this to “Never notify me” level, but this means that when you or apps make potentially unrecoverable changes to your system you won’t be notified. This is basically a feature of Windows 11 and it’s not granular enough to really be of much use.