Even though I’ve been using it for years, I didn’t realize until recently that WordPress compresses uploaded images to 90 percent.
The WP Resized Image Quality plugin adds an option in Settings that features a slider so you can change the compression level.
I get why the WP devs probably think compressing uploaded images is a good idea (they are wrong, but I get why they think this is a good idea), but compressing images and not building in a setting where this can be adjusted without adding a plugin or editing a PHP file is ridiculous.

