Why do my popovers deflate?

I’ve tried the Nordic Ware recipe - https://www.nordicware.com/recipes/petite-popovers/ - and the King Arthur recipe - https://www.kingarthurbaking.com/recipes/popovers - and they both deflate after coming out of the oven. The KA popovers came out more like dense egg balls with air pockets below them. The NW popovers usually come out mostly right, but they deflate quickly. I always weigh out everything I can with a scale that’s accurate to .1g I don’t have trouble with baking temps or times for anything else in my oven, but . . . What else might I be doing wrong?