I don't think FPS can do this(returning multiple keys in one license), you may need to request license when the key changes, or if possible, request the key before the key change by requesting the key earlier.

Maybe you can use the mediastreamvalidator tool to have a check with the stream, it may provide more information regarding to the stream format.

Did you get a valid license after calling renewExpiringResponseData and give it to iOS? Some old iOS version will raise error when calling renewExpiringResponseData(), but latest version seems ok. And do you know how to use AVAssetResourceLoaderDelegate to renew the license?

So both AVContentKeySession and AVAssetResourceLoaderDelegate don't work then, It's better raise a ticket to Apple. I had another issue that on iOS18 even the license expires but the video continues playing. May I ask if you have the similar issue? It happens in the device, not airplay. thanks.