His allies have questioned the messaging and depth of the ad-buying by the super PAC, according to two people briefed on the matter.

Source: https://www.nytimes.com/2023/11/22/us/politics/desantis-pac-chris-jankowski.html

Some ad-buying firms had recommended their clients pause ad spending on Twitter after Musk's takeover.

Source: https://www.channelnewsasia.com/business/exclusive-twitter-focus-video-commerce-business-revamp-investor-presentation-3568301?cid=cna_flip_070214

YouTube was one focus of the commission's investigation, which looked into whether Google was using the video sharing site’s dominant position to favor its own ad-buying services by imposing restrictions on rivals.

Source: https://www.postandcourier.com/aikenstandard/news/financial/google-should-break-up-digital-ad-business-over-competition-concerns-european-regulators-say/article_7a847a85-8471-520d-9b57-c14d85d288da.html