This userscript unsquashes inline images in comments by fetching the source image and downscaling it to 50%.
Requires *monkey extension to run (greasemonkey, tampermonkey, violentmonkey, et al)
Edit: also updated it to support the thread index
Not sure I follow you. I don’t have auto media preview on. This only uses the full-size images, it stops loading the downscaled thumbnails from the server. You can click to trigger a modal or you can middle click to open in new tab.
without the script, you click on the thumbnail and it opens the thread, you click the thumbnail again and it opens the full image. But with this script, the thumbnail in the thread is gone and cant be clicked.
Here’s an updated version that should handle all scenarios