After upgrading to Big Sur, Safari cannot download files because "the disk doesn't have enough space" though it does

After upgrading to Big Sur, I am unable to download files with Safari. I *am* able to do so with Chrome. Safari gives the message: "Safari could not download the file because the disk doesn't have enough free space."

1) I have 276.94 GB (8.63 GB purgeable) available

2) permissions for read/write to the Downloads folder is correct

3) Safari is correctly pointing to the Downloads folder

Googling didn't provide any clues, other than the obvious things to check (1-3 above).

Any ideas?