@Christian Beikov

According to the semantics of JPA, calling persist with a REMOVED entity will result in the entity becoming managed again.

I'm not questioning that approach at all. The only issue with this JIRA ticket is why an exception is thrown in one case and not in the other?
When this occurs, I want to be notified about it, whether I'm using a Hibernate session or the EntityManager.
It is disastrous that in one case an exception is thrown and in the other case not, even though it is the same semantics.
This is simply a bad quality of the software. It is your decision to reopen the bug and thus improve the quality of the software.