Looks like under the "show recipes that you have all the materials for" the strings "Left-click to toggle"and "Right-click for filtering options" are not in the locale table in curseforge

Those phrases have been added to the Skillet-Classic and the Skillet localization and the source files have been updated. The next build for both projects will pick up the current translations (which will still be English unless volunteer translators help out) for those strings.

I assume you are playing on a non enUS locale so please feel free to add the translation for your locale and if you can do both Skillet-Classic and Skillet that would be fantastic!

This should be fixed in Skillet-Classic 1.22.