I have files that are transferred using rclone from a remote server (with SFTP) to my NAS and then moved to my Mac mini that have this attribute.
It seems that macOS 13.2.1 Ventura is unable to remove this attribute. Strangely enough, I dug up my barely working 2012 MacBook Air still running Mojave 10.14.6. I was able to remove the extended attribute using the command xattr -c filename
If I use xattr -d filename even in Mojave, it doesn't remove the attribute.
Using the same (-c) command on Ventura apparently does nothing. It's really not a solution, but it's interesting that Mojave works but Ventura doesn't.