I looked into this since it was an issue i was facing also. Aparently this is a bug that has been around for a longer period as described in this issue.

The bug was related to files being added to uploaded files even if upload failed. I created a PR for it that has now been merged. And from prime vue version 4.3.3 files will not show up as completed after an upload failure anymore. They wont show up as failed either, but that can be done outside of component if you listen to the @error event.