Probably addresses distributed by IANA directly before RIPE (and RIRs in general) existed[1].

I don't know if they actually cannot be revoked by RIPE (or ARIN or someone else), though.

[1] https://www.ripe.net/manage-ips-and-asns/legacy-resources/le...

It's very hard to see how RIPE could not revoke them. They might not have much of a process, but that doesn't mean they couldn't invent one.

And if the argument is that you could undertake legal action to get them not to do that well... given you've essentially just argued you are not subject to the law due to the status of Kosovo's government and you'd likely be defending actions that are illegal in any other state best of luck with that.