matrix-synapse: Service failed to start due to missing requirement

Matrix-synapse service fails to start On Debian Buster, Freedombox version 21.1.

journalctl:

Feb 04 09:24:11 fb systemd[1]: Starting Synapse Matrix homeserver...
Feb 04 09:24:13 fb python3[25201]: ERROR:root:Needed optional psycopg2>=2.8, got psycopg2==2.7.7
Feb 04 09:24:13 fb python3[25201]: Missing Requirements: 'psycopg2>=2.8'
Feb 04 09:24:13 fb python3[25201]: To install run:
Feb 04 09:24:13 fb python3[25201]:     pip install --upgrade --force 'psycopg2>=2.8'
Feb 04 09:24:14 fb systemd[1]: matrix-synapse.service: Control process exited, code=exited, status=1/FAILURE
Feb 04 09:24:14 fb systemd[1]: matrix-synapse.service: Failed with result 'exit-code'.
Feb 04 09:24:14 fb systemd[1]: Failed to start Synapse Matrix homeserver.