Hello tomfromliessel,
Thank you for using Apple Support Communities. Thanks for following up with us. There are only two options to download the full-resolution photos from iCloud, the steps are below:
1.) You must download the photos from the iCloud website by selecting "Unmodified Original".
2.) You did mention that you're selecting "Most Compatible" due to format reasons. If that's the case you will need to use iCloud for Windows.
Currently these are the only two options to download the full-resolution photos from iCloud. Apple does appreciate all feedback regarding their products, services, and features. If you'd like to provide feedback on your experience with their products or services, you can do so using this link: Legal - Unsolicited Idea Submission Policy - Apple
Thank you for using Apple Support Communities. Take care.