Hello,
I confirm that replacing the server name webdav.pcloud.com by ewebdav.pcloud.com seems to solve the problem.
Indeed, I followed the following procedure:
- Stopping the pcloud application (pCloud Drive under Linux)
- Removing of home/.pcloud and home/.config/autostart/pcloud.desktop (as indicated by the pCloud support and to start again on a good basis…)
- Restarting the pcloud application that needs to be reconfigured (especially the local folders to synchronize; it then seems to recheck in upload and download all the synchronized files…)
- Modification of the server name in my Duplicati backups by ewebdav.pcloud.com (many thanks to ts678
see https://www.techstream.at/pcloud-via-webdav-ansprechen-geht-das/ or https://www.zotero.org/support/kb/webdav_services) - Regeneration (“delete and repair”) of the local database of each backup (just to start again on a good basis…)
- Manual launching of backups
What’s incredible is that pCloud’s support did not suggest changing the name of the server following the migration from a US server to a European server…I have reported to pCloud support the necessary change of server name depending on data region … 
Best regards