Synonyms that are in the dictionary are marked in green. Synonyms that are not in the dictionary are marked in red.
Antonyms that are in the dictionary are marked in green. Antonyms that are not in the dictionary are marked in red.
They're supposed to check if the accessor is, by some definition, authorized to access that URL.
Source: https://www.seroundtable.com/google-cdn-injected-security-seo-34894.html