What I don’t like is that in many cases sportsbooks know day 1 that a player is multi-accounting. They let him play in case he loses. This isn’t limited to Rainbet. Of course it matters on how the multi-accounting was detected.
It depends on how the system detect the abuse. In most of cases, security check starts when to withdraw because nothing should be suspicious for depositing or betting.
I agree with you that it becomes a commun practice by casinos to let the user make deposits and enjoy betting even after abuse detection but there are no ways on how to prove this. With Rainbet, I don't expect this to be the case because this is one of the few times to see accusation against them and the amount isn't that big to be taken in this way. We don't know how much OP has deposited and his activity with the other 8 accounts.