Postgres Logical Replication - "replication slot "mysub" was not created in this database"
CREATE SUBSCRIPTION mysub CONNECTION 'dbname=testha host=192.168.150.210 user=postgres password=postgres port=5432' PUBLICATION mypub;



What was the output of this command?

You should have gotten something like either:

NOTICE:  created replication slot "mysub" on publisher 
CREATE SUBSCRIPTION


Or 

ERROR:  could not create replication slot "mysub": ERROR:  replication slot "mysub" already exists


It sounds like what happened here is that at the time you created the subscription, the publisher was running as expected.  But then you did something weird, like disconnect the subscriber, rename the database "testha" on the publisher to something else, make a new "testha" and try to reconnect the subscriber to that.