Yes, Apple has written the ipadOS store rules in a way that excludes GPL software. Now, if we could get the agreement of all 600+ people who have copyright in Krita to sign a waiver, we might be able to try to put Krita in the ipados store, but very likely Apple would still refuse Krita because it needs access to the file system.
That’s what’s blocking us from getting into the macos app store right now, btw.