Hi @charlotter
Thank you for the information.
I did some extra tests and I would like to update my previous reply:
I was able to replicate it on my lab site.
I indeed was able to see a quality loss on my end, but it was because the Smush > Resize was defined to 500x500px and on my page, the image was loading on a 1200px container which will blurry the final result.
But there is a difference on your website, it is loading the original image instead of any thumbnail.
The thumbnails are versions of images that WordPress create, you can find more on:
https://wpmudev.com/blog/wordpress-image-sizes/
On the page it is loading the original image size:
https://monosnap.com/file/BToFfdXHiKHPuw7XahvdIxs1GTsYnn
This image won’t be Smushed by Smush Free version only on Pro version, which means the issue is not coming from the plugin.
By default the WordPress already compress any image to 80%, please find more on: https://www.wpbeginner.com/wp-tutorials/how-to-increase-or-decrease-wordpress-jpeg-image-compression/
You can increase it to 100% however we don’t suggest it.
Let us know if you have any additional questions about it.
Best Regards
Patrick Freitas