IVR registration is intended for internal use. When a bank suspects that you are or have been involved in a fraudulent incident, you may be registered in the bank's own IVR.
You will be put on a warning list, so to speak, so that you will be watched extra closely by the bank. Compared to the blacklist of EVR registration, that sounds a lot less serious (and it is).
This is because an IVR registration can only be seen by employees of the bank itself. Moreover, they only see your name and date of birth, but no details about the incident that led to registration.
Should you face an IVR registration, the most logical step is to simply go to another bank. After all, there they cannot see your registration.
However, it should be kept in mind that any organization within an umbrella group can see the registration. Consider a bank with multiple trade names, such as ABN AMRO Bank. If you are registered by one, the rest will see it as well.