I have been working with Apple Support for weeks on this same issue. I've got a brand new high-end laptop - 12th gen Core i7, 64GB RAM, 2x2TB SSDs in RAID 0. I have to use a native Windows 11 machine for school. I have tried uninstalling and reinstalling. I have tried disabling and re-enabling iCloud Drive. I finally have just let it continue to sync. The last time I re-set it was August 21, 2022 at 1:04PM. Since that time, I have been running my laptop nearly 24/7 in order to allow it time to sync. It still isn't done.
To clarify, I have not asked iCloud Drive to download any files. I have not selected "Always Keep on this Device" for any files. This is just the initial sync of what I would guess is just metadata.
I can see using ProcMon64.exe that iCloudDrive.exe is working furiously in the background accessing a file C:\Users\XXXX\AppData\Local\Packages\AppleInc.iCloud_XXXXXX\LocalCache\Local\Apple Inc\iCloudDrive\iCloudDrive.db. I estimate that it is reading or writing to that db file 70,000 times a second. That is not the only thing that it is doing, but it is the vast majority of what it does. The process rarely uses the network. It uses about 8% of my processor at all times. I mostly am syncing from home with 1000 down/100 up fiber and WiFi 6.
I have sent multiple logs to Apple engineering. So far, they are saying that everything is working correctly, which obviously can't be the correct answer.