Comment 7 for bug 1801863

@Brian - verified on a real machine and a VM. In the VM I could do extra confirmation by snapshoting the system so I could roll back to repeat the same snap installs several times before and after update, to confirm the fix and change in behaviour.

From a tested install after update:

~$ apt-cache policy plasma-discover*
plasma-discover-snap-backend:
  Installed: 5.13.5-1ubuntu6.1
  Candidate: 5.13.5-1ubuntu6.1
  Version table:
 *** 5.13.5-1ubuntu6.1 500
        500 http://gb.archive.ubuntu.com/ubuntu cosmic-proposed/universe amd64 Packages
        100 /var/lib/dpkg/status
     5.13.5-1ubuntu6 500
        500 http://gb.archive.ubuntu.com/ubuntu cosmic/universe amd64 Packages
plasma-discover-common:
  Installed: 5.13.5-1ubuntu6.1
  Candidate: 5.13.5-1ubuntu6.1
  Version table:
 *** 5.13.5-1ubuntu6.1 500
        500 http://gb.archive.ubuntu.com/ubuntu cosmic-proposed/universe amd64 Packages
        500 http://gb.archive.ubuntu.com/ubuntu cosmic-proposed/universe i386 Packages
        100 /var/lib/dpkg/status
     5.13.5-1ubuntu6 500
        500 http://gb.archive.ubuntu.com/ubuntu cosmic/universe amd64 Packages
        500 http://gb.archive.ubuntu.com/ubuntu cosmic/universe i386 Packages
plasma-discover:
  Installed: 5.13.5-1ubuntu6.1
  Candidate: 5.13.5-1ubuntu6.1
  Version table:
 *** 5.13.5-1ubuntu6.1 500
        500 http://gb.archive.ubuntu.com/ubuntu cosmic-proposed/universe amd64 Packages
        100 /var/lib/dpkg/status
     5.13.5-1ubuntu6 500
        500 http://gb.archive.ubuntu.com/ubuntu cosmic/universe amd64 Packages
plasma-discover-flatpak-backend:
  Installed: (none)
  Candidate: 5.13.5-1ubuntu6.1
  Version table:
     5.13.5-1ubuntu6.1 500
        500 http://gb.archive.ubuntu.com/ubuntu cosmic-proposed/universe amd64 Packages
     5.13.5-1ubuntu6 500
        500 http://gb.archive.ubuntu.com/ubuntu cosmic/universe amd64 Packages