Storage Type is the first choice on the Destination screen, but pCloud is not available.
Possibly you are using “Local folder or drive” but it is actually pCloud Drive virtualized.
Some previous reports of errors doing it that way are:
Error during auto backup
Error on linux mint
Possibly you are using WebDAV.
pCloud natively supported by Duplicati? discusses the unreliability of WebDAV usage,
although there was a comment there about a European server that was more reliable.
Recovering by purging files discusses a generic path of recovery from corrupted files.
Removing the corrupted file triggers it. Do you know the names? If not, try watching in
About → Show log → Live → Warning
A concern is you might have other corrupted files. The download-to-check is a sample.
It is possible to test all files, but the best way depends on things like the Storage Type.