So I agree with all that is said, and I was very agitated by the fact all files were moved off to the Cloud without my permission. That is a complete and utter failure to communicate by MS. However, I upgraded to 12.1 on Sunday, turning off OneDrive. Then I restored my OneDrive files to ~/Library/Cloud Storage/OneDrive and turned on OneDrive. Next, I clicked on all of my top-level folders and chose "Always Keep on this Device." So far, everything looks good and is working as expected. I tried to do it without restoring, and it got all tied up, I guess because it was 50GB that had to be downloaded, and I was not patient.
Regarding the Symbolic Link implementation with OneDrive, that should not be an issue. I used Symbolic Links for years with Unix and Mac in particular and Dropbox and never had a problem.