That’s fair, my dentist was just all “what are you doing different because you have no cavities and hardly any plaque buildup” when I bought one. I do like the rotating ones better than the up and down ones tho. Maybe that matters for foam?
Toothpaste foam is a function of a chemical put in lots of toothpaste called Sodium lauryl sulphate (SLS). You can buy brands of toothpaste without that in it and you don't get that foam. Check your toothpaste you're using right now. I bet its in yours.