Provided the sponsored content is labelled "sponsored content" this is above board.

If it's not labelled it's in violation of FTC regulations, for both the companies and the individuals.

[ That said... I'm surprised at this example on LinkedIn that was linked to by the Washington Post - https://www.linkedin.com/posts/meganlieu_claudepartner-activ... - the only hint it's sponsored content is the #ClaudePartner hashtag at the end, is that enough? Oh wait! There's text under the profile that says "Brand partnership" which I missed, I guess that's the LinkedIn standard for this? Feels a bit weak to me! https://www.linkedin.com/help/linkedin/answer/a1627083 ]