Probably candidates and influencers should disclose if they are being paid. After all once you are getting paid, you ARE in the advertisement business.
We kind of have that in Germany regarding Youtube and promotional content ("Schleichwerbung" in German, literally "sneaky/sneaking ads"). The problem is that rules are vague so you get endless "this video contains ads"-infos even for those that don't because producers want to be on the safe side when they talk about or show a product. That diminishes the value of the message, because "it's on every video, whatever", just like people react to cookie consent banners.
If you make it too narrow, he'll gift them plane tickets, if you make it to wide, is google giving you free hosting on blogger already something you need to disclose on every post?