Thumb drives read-only in Big Sur?

Mac Mini M1 16GB macOS Big Sur 11.2.1. When opening documents on a USB thumb Brive, specifically in Garageband, I can't save them back to the thumb drive (formatted Fat32). "You don't have permission." Check permissions on the thumb drive, and it says I have "custom permissions." No option to change.

I know that I can reformat the drive, and this will fix it. But it's every. single. drive. I move a lot of files around via sneaker net, and this is getting old fast. This seems like Big Sur being super overzealous in its permissions control – but only with GarageBand files. Somewhere, there has to be a setting I can change to turn this off. Thanks!