I'm having the same issue and it is very annoying and really degrades the end user experince.
I've got an iPhone SE, and ComboBox set to size 25 font. When I click on the combobox, the application is zooming in substantially. After you pick a selection, you have to click out of the combobox, and then two finger manually zoom out (without clicking on any other part of the application).
Same over here. I've got users who stop using PowerApps because of this annoying issue. Don't even understand why this zooms in.
Although the pinch-zoom functionality is said to be an accessibility aid, I believe it did create unintended effects. For example, as @Specoop has mentioned when a user selects a combo-box or a drop-down with a single tap gesture the screen zooms-in clipping items off of the view area, which should be displayed. I have made a screen-recording of this exact issue using an iOS device. Notice, right away (first 5 seconds) I tap the combo-box to display its options and the screen zooms-in clipping parts of the screen. I then use two fingers to zoom out. Additionally, I am aware that iOS has an accessibility option to zoom and I did confirm that setting is disabled on this device. The iOS zoom setting is not the cause of this issue. Note: when retrying this process by using the back button and reselecting the combo-box, now the combo-box opens its lists and is displayed correctly without zooming. However, this issue is and should be able to be reproduced.
This is so annoying. Please fix!
Still no option to disable this?
Please fix! Very Annoying...