Apple uses AES encryption for iCloud Photos: https://support.apple.com/en-us/HT202303 https://support.apple.com/en-us/HT202303 Underlying cloud providers that

Apple uses AES encryption for iCloud Photos: https://support.apple.com/en-us/HT202303 https://support.apple.com/en-us/HT202303 Underlying cloud providers that Apple uses e.g. AWS may not have the key but Apple definitely does. And that key could be embedded in a CSAM detection app. So unless you work for Apple and have definitive proof that they do not have such an app I think we should assume they do.