Over the last year and a half, they've added very few new features. And mostly the 'new' things just released are simply expanding the use of the GPU for encoding/decoding. Upgraded performance with some of the complex media like RED. So ... exactly what new features should they not have worked on?
I've worked daily with Premiere for over six years now, and have never had your issue happen. Yes, I've seen it posted here a couple times. But what you're describing sounds like what happens when the OS puts a 'write protect' on a file. Both the Mac and Windows OS's have been doing things like that on updates over the last year, and it is a right royal pain.
Especially on the Mac side, some users nearly have to wrestle their computer to the ground after an update to restore read/write privileges to a folder here and there. And that's certainly not something any of us look for off the bat. Until you've had that hit before.
And yes, I've recently had issues where Win10 would allow say Premiere 2019 to do things in the various Premiere setup files but it wasn't allowing Premiere 2020 to do the same with its files. Even setting Premiere to run with admin privileges didn't stop it. I had to go in an set each folder, and in them some files to any user access for read-write before 2020 started 'behaving' properly.