How to find the attachment file has not been smushed?

@ngoctam1011, you can switch to list mode in Media Library and Click on the WP Smush column.

It’s sortable, so when you click, it’ll arrange the images in order of smushed and not smushed images.

Here is a screenshot: https://monosnap.com/file/WbQhdPrIcoWZDKYcn5Yl49VmmY8RoZ

Cheers

I had over 800 images on my site, it shows 1 image which is not sumushed only.
I cannot find it following your instruction.

@ngoctam1011, What happens when you try to sort the WP Smush column in list mode in Media Library?