Maxscale needs to check how up-to-date the slave is, before move traffic to it.

If somehow, slave (node1) can't connect to master and it's retrying again and again
We'll see the below state in show slave status

Slave_IO_Running: Connecting
Slave_SQL_Running: Yes
..
Seconds_Behind_Master: NULL

In maxscale 'list servers' we could see the node1 status as 'Slave, Running' and maxscale is routing connections to the slave in which replication is broken.

┌────────┬─────────────┬──────┬─────────────┬─────────────────┬─────────────┐

│ Server │ Address     │ Port │ Connections │ State           │ GTID        │

├────────┼─────────────┼──────┼─────────────┼─────────────────┼─────────────┤

│ node1  │ 10.66.21.38 │ 6603 │ 17          │ Slave, Running  │ 1-2-3312917 │

├────────┼─────────────┼──────┼─────────────┼─────────────────┼─────────────┤

│ node2  │ 10.66.21.37 │ 6603 │ 49          │ Master, Running │ 1-2-3319973 │

└────────┴─────────────┴──────┴─────────────┴─────────────────┴─────────────┘

Since this 'node 1' replication is already broken maxscale status for this node should be in 'Running' state and no connections should be routed to this slave. But this is the current behaviour which needs to be changed. On the long run, we probably need to implement some kind of grading system, where the monitor or router checks how "up-to-date" the slave is.