Pixelated Images

https://houghtonhorns.com/product-category/new-horns/

If you scroll down a little to “Stomvi Titan Seis”, the image is extremely pixelated. Above is is the “Stomvi Elite”. I took both those photos with the same camera in the same location on the same day and uploaded them using the same technique — why is one blurry and one clear? Deleting the Titan image and re-uploading it does not fix the problem; I’ve re-uploaded three times and it still looks terrible.

The problem looks like it’s spreading: the images at https://houghtonhorns.com/trombones/ used to look clear, but now they’re looking awful.

I’m using the WooCommerce, the OceanWP theme, Imagify to optimize image size, and Jetpack’s Image Performance to optimize speed. I suspect two or more of those plugins are interacting poorly, but turning them on and off isn’t helping. Re-optimizing the images with Imagify doesn’t seem to help either.

I would appreciate any help you could give me in narrowing down the cause of the problem. Thank you!

The page I need help with: [log in to see the link]