Resolved by restoring com.espocrm.cloudronapp@2.20.4
Then updating to Cloudron 2.20.5
Then updating to Cloudron 2.20.6 (EspoCRM 9.3.6)
I had a lot of apps going into error when 9.1.6 got installed on a reboot.
Upgrading to 9.1.7 (out of beta) fixed most of them, but EspoCRM needed this intervention.
Just FWIW if others are encountering the same.