What is the .tmp.driveupload folder in Mac documents

When I select the Storage tab in About This Mac, then select Manage, it shows the large files and many, many of these have a 5-digit number like 43001. All of these similar files are in a folder called .tmp.driveupload, which is in my Documents folder. I have my Documents folder in iCloud and I have Optimize Storage turned on. When I Get info on this folder in Finder, it tells me that it contains over 4300 files, all of which have these 5-digit names. Their file sizes are small in Finder; for example the file called 43001 has 160bytes. But in the Manage window in About my Mac/Storage, it says this same file is 767.7 MB. Four other of these 5-digit files also are 767.7 MB. Also 20-30 other 5-digit files have the size of 740.1 MB each.

What are all of these files? What is the .tmp.driveupload folder? Can I remove this folder and its files? And why are the file sizes different in Finder and in About This Mac/Storage/Manage?

I'm running macOS Monterey 12.0.1 on an M1 MacBook Air.