Found out that the battery lasts slightly longer than usual, memory management is good.. Haven't encountered anything else yet!
Probably algorithms for better battery, memory management and few other fixes! The Note 20 Ultra was sucking battery life like nobody's business! I can get through the day and charge late at night! I don't use the Super Fast Charging feature as it degrades the battery faster..
Backup in Secure Folder didn't work after Android 11 update - that was a major bug, took them long enough to fix it.
They probably fixed even more bugs we weren't aware of and made some optimizations.