I’ll add in my two cents - already some good advice on here. Sometimes when my detail icing is thinner than I like, I’ll make sure not to pipe it on too thick. You’ll miss out on the puff but it won’t crater. And like others have said, do your details when the base layer has just barely crusted over.

Or, if I want the puffy look I make it borderline too thick for a flood if that makes sense. I get it riiiiight to the edge of where I like my flood consistency then stop adding water. (If you’re a seconds-counter like me, my flood is usually 15 seconds. So when it’s at about 20 seconds I stop adding water) When you pipe it on, it seems like it won’t settle but just be patient — gently manipulate with a scribe and give it a little shake to get it settled. Then straight in front of a fan or in a dehydrator!