nofollow, sponsored and ugc
Link attributes that tell search engines a link is not an editorial endorsement: rel="nofollow", rel="sponsored" and rel="ugc".
rel="sponsored" marks paid or affiliate links, rel="ugc" marks links in user-generated content such as comments, and rel="nofollow" covers any other link a site does not want to vouch for. Google introduced sponsored and ugc in 2019 and treats all three as hints rather than strict instructions.
Marking paid links is what keeps them within Google's policies.