You know (or now you do:) that Samsung released the AUHD September update for the S21 series! This is a rather small update, only 200 MB and it`s rather only an update of the security patch now with September Security Patch... but nevertheless I have tested full the rom!
You can check my video here and directly jump to sections you are interested in:
Video Quick Guide: 00:00 - Intro, ROM Installation, Clear Cache & Optimize all Apps! 01:57 - September AUHD ROM info 02:25 - Camera Start/Close Test 03:12 - Camera shutter lag test (taking single & multiple photos) 03:52 - App opening/closing and App switching test 04:41 - Geekbench test and comparison vs August & July results! 06:18 - Version Checks, One UI Home, Camera App, Biometrics Patch 07:00 - Samsung Stock Application Updates Available 07:24 - AnTutTu test and comparison vs August & July results! 08:27 - Video Outro