As seen by what? AUR package makes Duplicati more secure (rather than root) so it has access issues.
About → System info → Username is one way to see the user, but various system tools can also do that.
About → Show log → Live → Warning should be able to give more info on why it can’t access those files.
Sampling around, though, it looks like some are root-only, which is weird if Duplicati is really run as root…