I read a series as a teen that I'm fairly sure had some product placement - characters mentioned multiple times how much they liked Smuckers preserves.

Interestingly, the series had multiple viewpoint characters with each book narrated by one, and one of them had much more product placement than all the others - I only remember Cinnabon being mentioned outside her viewpoint books, or her being the one to mention a brand. I wonder whether it was a result of the author method writing, as that character was also the most ruthless of the group.