The influencer has received something for free. There is an advantage. Most influencers want to make it clear with the hashtag #nospon that they have not received any extra compensation for it. That it is a barter deal, so to speak. However, this hashtag can cause people to think that someone has paid for something themselves. That is simply not true and that suggestion should not be given. So another creative solution will have to be found for this.
In theory, both the influencer and the advertiser are responsible for the expression going well. This special lead means that press packages also include a briefing, flyer or at least a message. This must state that the influencer must report that it is advertising. Suggestions can of course be made, for example to use the word #received or #presspackage, so that it comes across as friendlier than #spon or #ad. According to the Social Media Advertising Code, the advertiser is responsible for providing the correct information or instructions.
Both the influencer and the advertiser are independently responsible for the expression itself. They can therefore both be held accountable. Also by the Advertising Code Committee. In practice, however, the advertiser is always held accountable. Also because it is often a competitor who finds an expression annoying and files a complaint about it. Or has one filed by a consumer.
The result is that all statements and recommendations are published. Only when a party does not comply with this, it is blacklisted. Going to court is also possible and the ACM may also enforce, but that only happens rarely.