3.38.1 fails to see my scanner. The 3.36 version in the man repository immediately sees it (an HP OfficeJet Pro)
tim@indigo:~$ snap run simple-scan --debug
(simple-scan:67422): Gtk-WARNING **: 14:50:11.432: Theme parsing error: gtk.css:1566:23: ‘font-feature-settings’ is not a valid property name
(simple-scan:67422): Gtk-WARNING **: 14:50:11.434: Theme parsing error: gtk.css:3616:25: ‘font-feature-settings’ is not a valid property name
(simple-scan:67422): Gtk-WARNING **: 14:50:11.434: Theme parsing error: gtk.css:4078:23: ‘font-feature-settings’ is not a valid property name
[+0.00s] DEBUG: simple-scan.vala:2012: Starting /snap/simple-scan/707/usr/bin/simple-scan 3.38.1, PID=67422
[+0.70s] DEBUG: app-window.vala:1990: Loading state from /home/tim/snap/simple-scan/common/.cache/simple-scan/state
[+0.70s] DEBUG: app-window.vala:1969: Restoring window to 600x400 pixels
[+0.79s] DEBUG: scanner.vala:1556: sane_init () -> SANE_STATUS_GOOD
[+0.79s] DEBUG: scanner.vala:1562: SANE version 1.0.27
[+0.79s] DEBUG: scanner.vala:1623: Requesting redetection of scan devices
[+0.79s] DEBUG: scanner.vala:832: Processing request
[+1.13s] DEBUG: app-window.vala:2065: Saving state to /home/tim/snap/simple-scan/common/.cache/simple-scan/state
[+3.88s] DEBUG: scanner.vala:341: sane_get_devices () -> SANE_STATUS_GOOD
[+3.88s] DEBUG: scanner.vala:1623: Requesting redetection of scan devices
[+3.88s] DEBUG: scanner.vala:832: Processing request
[+3.98s] DEBUG: app-window.vala:2065: Saving state to /home/tim/snap/simple-scan/common/.cache/simple-scan/state
[+6.71s] DEBUG: scanner.vala:341: sane_get_devices () -> SANE_STATUS_GOOD
[+6.81s] DEBUG: app-window.vala:2065: Saving state to /home/tim/snap/simple-scan/common/.cache/simple-scan/state
[+16.71s] DEBUG: app-window.vala:2065: Saving state to /home/tim/snap/simple-scan/common/.cache/simple-scan/state