The release notes of iOS 18.4.1 only include the generic 'This update provides important bug fixes' but do not mention a fix for this. Does anyone know whether this got fixed or not?

I was able to resolve this issue by revoking all certificates that were created by Xcode Cloud and building again. You can do that here: https://developer.apple.com/account/resources/certificates/list

I was able to resolve this issue by revoking all certificates that were created by Xcode Cloud and building again. You can do that here: https://developer.apple.com/account/resources/certificates/list