What even would meet your standards here? Only an ad that started "Hey, kids!"?
Juul was buying ads on Cartoon Network/Seventeen/Nickelodeon and youth education sites. They got sued for it. They then fired the ad firm that developed an adult-oriented campaign for them in favor of the vaporized campaign which I definitely see plainly targets teens -- and the courts agreed, since they paid over $400 mil in fines because of it.
Companies do what they can to maintain plausible deniability. But it's also an absolute fact that the fruit/candy-flavored vapes are vastly more popular among youths. The FDA has entire teams dedicated to "advising" producers on how not to market these things to kids based on expert advice.
Your position here is one where you default to giving the producers of harmful, addictive products the benefit of the doubt. When I see Puff Bar being ranked among the most popular vape brands for teens, my assumption is that there is actual malice leading to that position.
And to be clear, the youth vaping market did not exist until the era of Juul reinvented it through advertising. These were not particularly new products, just new ways of selling them. Smoking was solidly on the decline among teens. It was new sales strategies that reversed that trend.