X_REPLICATION_SLOT_INVALIDATED
Means
the replication slot was invalidated
Typical cause
postgres invalidated the replicator's slot (wal_status = lost): it fell further behind than max_slot_wal_keep_size allows, so the WAL it needed is gone and it can never stream again
Fix
SELECT pg_drop_replication_slot('<slot>'); — then restart the replicator: it recreates the slot and every live window resyncs