I’m not convinced that source isn’t just spreading the urban myth. You’re going to have to come with something with more weight behind it than the webpage of a seller of heatpumps. Here’s another source saying it has nothing to do with eating: https://www.la-tour.ch/fr/conseils/se-baigner-apres-manger-faut-il-vraiment-attendre-3-heures
Sure they can