Relay Log Sequence Reset on Start Slave during FK fix cause Replication Breakage in MariaDB 10.6.19

While resolving a replication error related to a foreign key constraint, we observed that issuing a START SLAVE after dropping the foreign key unexpectedly reset the relay log sequence from relay-log.00004404 to relay-log.00000001. As a result, some transactions were not applied on the replica, and replication broke again after appearing temporarily healthy.

This behavior is unexpected because STOP SLAVE; START SLAVE; should not reset the relay log sequence under normal circumstances, unless a RESET SLAVE or CHANGE MASTER was explicitly issued — which we did not execute in this case.

This appears to be a destructive relay log reset triggered by START SLAVE, which should not occur and may indicate a bug in MariaDB 10.6.19.