I am fairly new to Groups.io and have the same 'issue'.? It doesn't matter what size the photo is when it is uploaded, it is blurry on a desktop screen (it is fine on a phone).?
I have uploaded a photo at 4000x 3000 (shows as 3.9 mb on the groups.io ) and a reduced version (to save space) at 1280x960 (shows as 1.1 mb), and they are both blurry when selected from the album,? If I select download, I get a crisp clear image on the screen so the image has not been corrupted during the upload.
Charlie Behnken