Screen sharing in FaceTime on iOS 15.1 not working in browser

In iOS 15.1 Apple has enabled the new improvements in FaceTime allowing you to invite users to a conversation using a link.

It is also possible to join using a modern web browser on a PC or Android device.

I am able to create the link and start a session between my iPhone running iOS 15, and my MacBook Pro running Safari, and video and audio works. However, when I share the screen on the iOS device, nothing appears in the browser.

Is this a known bug, a missing feature from the web version, or something else I am missing?

I have tried to look at the Apple documentation, and I do not see any mentioning of this as a feature missing from the browser-based clients, and I get no feedback on iOS 15.1 that the participant in the meeting cannot see my screen due to using a browser.

SharePlay for macOS is marked "Coming later this fall." on the feature list. It is reasonable to assume that the Web version of FaceTime either does not or will never support SharePlay.

I recommend you request this feature from Feedback Assistant or Apple.com/feedback, but I don't expect it any time soon.

https://www.apple.com/macos/monterey/features/