Comment 2 for bug 1921794

Please open terminal and set following variable:

  export SANE_DEBUG_DLL=255

Then run simple-scan with command:

  simple-scan

The output should be similar to:
https://gitlab.gnome.org/GNOME/simple-scan/-/tree/master

You could investigate which backend is taking so long from logs.

You could disable other (not hpaio) sane backends in file:

   sudo gedit /etc/sane.d/dll.conf