It's one thing if the author decides to do it (although it might not go down well with their readers anyway) and a completely different thing if a publisher does it without the author's knowledge. But, to say something positive, it was at least identifiable as an ad and not "seamlessly" integrated into the text.

Some not-so-reputable print magazines still do something similar to this day: embed ads that have more or less the same layout as the actual articles, praising some product. However these must be clearly labeled with the word "ANZEIGE".

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.

Specifically her novel "The Bulgari Connection"