I was googling to find out if anyone found the 'stage manager' useful as I've been trying it for a few weeks on my MacBook 16" but switched it off today.
Specifically - it stops me from dragging files from Finder into an upload box in a web browser. Overall I found using it very much like not having it at all, except it hides apps you're not currently interacting with and presents them for you again when you want to use them with a flourish, making drag & drop between applications impossible.
I wonder - have I missed the point? It just seems to be eye candy that just stops me from doing some things I used to be able to do. I've not discovered anything new that it offers.
MacOS has a perfectly working window manager already so it doesn’t make much sense there.
On iPad, the only options are Split View and Stage Manager, and Stage Manager offers far more flexibility. The thing I appreciate most with Stage Manager is I can now open apps that force you to portrait mode in landscape via window mode.