iphone 12 pro (ios 15.5) does not register key pressed during support calls

I have noticed over the last several months that when I am on a call to an automated support line which requires to press the keypad to select a menu item, it sometimes does not register the key press. I haven't quite figured out the pattern or if it is something I am doing which is causing the issue (like pressing the button too long, too early, etc), but without fail, if I call back, it works the second time.

Becoming very frustrating, hence the post.