The replica tools-db-2 is currently lagging 18 hours behind the primary tools-db-1 (Grafana chart). This is (correctly) triggering the alert ToolsToolsDBReplicationLagIsTooHigh.
SHOW SLAVE STATUS\g in the replica shows the replication is active, but it's lag is increasing (little by little now, started suddenly).
This happened before (T343819, T341891 and T338031). Both times the replica caught up after a couple of days, without any intervention. I will check if the database causing this issue is the same or a new one.