The same procedure as... ;)
Temporary fix for Ubuntu 18: Downgrade...
sudo wget https://dl.grafana.com/oss/release/grafana_8.1.7_amd64.deb
sudo dpkg -i grafana_8.1.7_amd64.deb
Or, have a look:
https://talk.plesk.com/threads/advanced-monitoring-extension-not-working-with-grafana-8-0-0-1.361060/