The new attributes for sponsored and (UGC) user-generated contents.
rel="sponsored": You can use this attribute to identify the links on your site that were created as part of sponsorship or an advertisements or other compensation agreements.
rel="ugc": This one is value to recommended for the user generated content, such as forum posts and comments.
Other than that, you can use the no-follow like this:
rel="nofollow": This attribute is for cases where you want to link to a page but Google said, don’t want to involve any type of endorsement, or passing along ranking credit to another pages.