Apple gave Zoom access to the iPad camera API for special multitasking feature
As discovered by app developer Jeremy Provost, Apple gave Zoom access to a “private iPad camera API” that allowed the video calling platform to become the only other platform, besides Apple's FaceTime, to use the camera during iPad Split View multitasking. This feature is now only available on Zoom and this gives them an advantage over other video calling solutions. The Split View feature allows users to access Twitter, or a notes app, etc while being on a video call.
Provost explained in his blog post that when he discovered that Zoom could take advantage of the Split View feature, he started searching for the process so as other developers could use it too. He asked Zoom about it and was informed that it was a “private process” and available “only to those deemed worthy by Apple”. To receive access to some API, Apple has to give an “entitlement”, which is essentially a privilege that grants execution rights for particular capabilities.
Speaking about HomeKit Entitlement, Apple explains - “For example, an app needs the HomeKit Entitlement — along with explicit user consent — to access a user's home automation network. An app stores its entitlements as key-value pairs embedded in the code signature of its binary executable.”
While Apple does provide public documentation and outlines the process for requesting access to entitlements, Provost also discovered that there isn't a public process for requesting this API in particular that Zoom has access to. It is called the com.apple.developer.avfoundation.multitasking-camera-access and unlike CarPlay there is no public process to request this. Also, its existence is not documented by Apple publicly, you can Google it, but it will take you straight to the Zoom Developer Forum.
It is not known why Apple only gave Zoom access to this feature, the company has said that it treats all developers equally. But there seems to be a list of sorts that you need to be on to be able to get these privileges. For example, it was revealed at the Apple vs Epic trial that Hulu had special API access. There are emails that contain an internal question about why Hulu can switch between App Store billing and Hulu billing. It turns out that Hulu is a part of a list of “whitelisted developers” who have access to the subscription cancel/refund API. Apple had given Hulu initial access to this API to support upgrade and downgrade plan changes before it got natively built-in to the App Store.