[keycloak-user] password history not always correctly considered

Hello, I have a realm where password history was set to 3. When I try to set the password for an user too fast (via REST API), I'm able to use one of the passwords that should be recorded as not usable. When I put a small sleep between the password changes (aprox. 300 ms), the usecase works fine - so I'm not allowed to use any of the 3 recorded password from the history. I tested the case using 1.9.3 Final and 2.2.1 Final with same results. It looks to me like a bug, isn't it? Thank you for the answer&best regards, Bystrik