@Smurf67: have you tried heading to the Samsung Notes app > Tap the 3 lines in the top left > Tap the cog in the top right of the pop up window, and checking the 'Sync with Samsung Cloud' and 'Sync to Microsoft OneNote' options to see if you're able to restore your notes from here? While you're here, tap on 'Import notes' for further options (Phone, Samsung account and Google Drive).
I was curious so I downloaded and installed samsung notes. When I open, it asked if I wanted to sync previous notes. Maybe an uninstall reinstall will help. But check to see if anyone else has sucess or is it a total disaster to do so.