I'm going to miss it if it's a permanent removal. I do software demonstrations for a living and my team uses this feature regularly. While Zoom does offer the ability to share an iPhone/iPad screen via Airplay and/or cable connection, it requires changing what you're sharing with multiple clicks, which can interrupt the flow of your demonstration. Being able to have that same screen open in Quicktime means you can pop back and forth between that and whatever else you are sharing quickly using the Command+Tab functionality.