I'm going to go out on a limb here and estimate that there are exactly zero users glad the current behavior is the way it is - when you click the little radio button for 'Fields' here, the whole dropdown closes. Great! My next move totally wasn't just to click on one of those fields that I was trying to get. How smart that it closed for me! Very intuitive! Very Pro!
That's ok, I love clicking my mouse as many times as possible! When I go back to values, it does the same thing! More clicks!!
... for the love of god: Improve SQL Expression Builder - Esri Community