Yesterday, Apple announced some major changes to Stage Manager in iPadOS 16.1, slated to be released sometime in October, 2022. When they initially announced the feature at WWDC 2022, Apple stated that Stage Manager would be a feature exclusive to M1 iPad devices, such as the M1 iPad Pro and the M1 iPad Air. Stage Manager also brought proper external display support to iPadOS.
In a statement to Engadget, Apple revised Stage Manager’s feature set for the upcoming iPadOS release:
We introduced Stage Manager as a whole new way to multitask with overlapping, resizable windows on both the iPad display and a separate external display, with the ability to run up to eight live apps on screen at once. Delivering this multi-display support is only possible with the full power of M1-based iPads. Customers with iPad Pro 3rd and 4th generation have expressed strong interest in being able to experience Stage Manager on their iPads. In response, our teams have worked hard to find a way to deliver a single-screen version for these systems, with support for up to four live apps on the iPad screen at once.
External display support for Stage Manager on M1 iPads will be available in a software update later this year.
Apple to Engadget
Stage Manager for Older iPad Pros
That’s good that older iPad Pros, such as my 2018 iPad Pro (3rd-generation) will be able to use Stage Manager. Had I held out, I wouldn’t have needed to buy an M1 iPad Pro to conduct my initial testing!
Over the past two months, I not been using Stage Manager all that much. Instead, I’ve continued to use Split View and Slide Over. While it’s nice to be able to use up to four applications at a time, I dislike the constant window micro-management that Stage Manager asks from its users. Split View and Slide Over are by no means perfect, but the limited sizing and positioning of windows make these two modes easy (for me) to use and understand.
One of the reasons why I was intrigued with Stage Manager was that it would allow me to use other applications alongside MixEffect. The next major version of MixEffect, however, will bring Run in Background, a feature that allows iPadOS and iOS devices to keep MixEffect running through the use of Apple’s Picture in Picture API.

Saying Goodbye for now to External Display Support
An M1 iPad Pro running the latest Developer Beta of iPadOS 16.1 no longer shows the external desktop (see screenshot below from the previous iPadOS 16.1 beta), replacing it with the mirrored output from the iPad (or the contents of an app which supports rendering separate output to an external display).

With all the crashing bugs people have continued to report with the previous iPadOS 16.1 betas, this comes as no surprise. The segment of users who actually plug in an external display into an iPad must be small, so best for Apple to delay the feature instead of releasing it in what is clearly an unfinished state.