Do you see the low quality when you zoom? Or just in the regular feed? I can check the algo, but it is essentially scaling down to the number of pixels in the screen of the feed. When users hit the save button, it re-downloads to get the full res.
Discussion
Understood. This picture (like many), being a wide shot, lends itself to tapping to go full screen and zooming in.
I kept looking at it and was honestly questioning whether I accidentally forgot to upload without compression, then I zoomed in and checked the link to confirm the drastic difference in quality.
I provided zoomed screenshots in a previous comment and it's clear the difference when copy and pasting the link into a browser (on the same phone screen).
It was rather shocking to find that it looked so much better on my secondary client than on Amethyst.
Thank you for looking into and hopefully optimizing the scaling. Again, it's pretty apparent when you have a look for yourself.
Hope this helps!