Hi All - I got this reply from Patreon Support.
Hopefully the issue should be resolved :)
Thanks for your patience.
Hello there,
My name is Chet with Patreon Creator Support, and I am more than happy to assist you!
I am sorry to hear that your members have been experiencing issues while attempting to download your images from your Patreon page. I understand how frustrating this can be and I apologize for any inconvenience this has caused you both.
We recently experienced an issue with image uploads being compressed and degraded while we were going through an update in the process of how they were uploaded. This issue should now be resolved. However, if you and your members are still experiencing issues with your images being WEBP files, please let me know and I will continue to review this on the back end.
I hope this information has been helpful! Please let me know if you have any additional questions or concerns.
Thank you,
Chet