CC composite is great for compositing its own layer over itself again, the track mattes is good for tracking an alpha/luma of a layer above itself.
However, many times I'd like to composite, say an icon, over a circle shape - then animate each one independently (perhaps the circle scales up and the icon slides down to the centre of the circle), then, have the icon track the circles alpha channel so you only ever see the icon inside the circle.
Set matte doesnt often work as you are manipulating transform properties, and set matte seems to only work when both layers are the same dimensions or their default transform properties otherwise the matte is out of alignment.

The track matte works but you have to duplicate the circle layer and put it above the icon, then alterations to the circle animation would have to be replicated (barring fiddly pick whipping).

So, the feature would be like a track matte for any layer, essentially (could remove the track matte switch).
I think it could be a setting or check box in the "Set matte" effect, simply "track matte" which would track any layers matte/luma etc, as it appears in the composition, like it has been pre-composed but without having to pre-compose.

I hope this makes sense.

AE 2022 is unstable and have bugs. It keeps cashing and sometimes just won't opening, I have to force quit and restart.
I also got this error message when opening a specific project :
"Internal verification error, sorry! [no current context]".
I tried to reinstall AE, did not work, then I reinstalled CC desktop and all my app, and I still got this message.
I was hoping today's update was going to fix that, but no, I still got the error.
I had to downgrade AE to the previous version and now everything's fine. I miss the good old times when we bought Adobe on CDs, installed it and it worked. Now I feel like I'm always on a beta version of the Software, experiencing bugs like I'm a tester and not a customer. Plus, I didn't find a way to report a bug. What I'm writing here is not a "feedback", it's a complain.

Not sure if this is because of the upconverted AEP project file from CS5 or because of After Effects CC actually rendering slower, but I had a project started in CS5 take over 2x longer to render out in CC 2021 at 5 hours instead of 1.5 hours. I thought maybe an update to CC 2022 would help, but then the same project file ended up taking 13 hours instead.

Switched computers just in case and the results were the same. The project is pretty simple - just a PSD with layers broken out and slightly randomized movement for that animated look. The project opens and edits in After Effects just fine - it's only the rendering that takes forever in the newer versions. It appears to be related to how PSD layers are imported, since deleting the PSD layers removes the difference in rendering time; the PSD has only basic layers and no smart objects.

Export is through Adobe Media Encoder with the below settings:
Resolution 1920x1080
Format: H.264 MP4
Bitrate: VBR 1-Pass 12Mbps
Length: 2 min, 50 sec

PC specs are:
Windows 10 Pro 64-bit
i7-9750H 2.6Ghz CPU
32GB RAM
RTX 2060 GPU

Attached is a stripped-down version of the project with empty layers, so it's easier to test, but it exhibits the same problem. I have all the PSD layers cleared so there's no actual image, but it still has the performance hit. On CS5, it renders reasonably in 10 minutes. On 2021 it takes 30 minutes, and on 2022, it takes at least an hour - not sure on the final count since it's still rendering and less than 50% done.

Download test project here:
https://drive.google.com/file/d/1NW8cPQRbl3yMt9qCU0gLOodqYA_ZW3AR/view?usp=sharing

The old .flv codec that was discontinued years ago is truly a revolutionary codec that can make a standard alpha animation that would normally range anywhere from 200MB to several gigs into less than 10mb. There is still television software like JVC that uses that old format. I understand that flash had security issues and other problems, but as for the codec, it was the only alpha channel codec that made picture perfect animations even smaller in size than most non-alpha codecs. There is no danger for hacking a movie file. For this reason, for internal performance of your own and for personal storage for extra large and bulky alpha based animations, the FLV codec should be reconsidered. While flash can remain it's grave, the codec is greater than anything you have and could improve performance significantly. Even if you rename the extension to something proprietary, please bring back or reverse engineer this codec as it will significantly make your product better. It isn't important that other players can't support this because alpha channel renders are used for production purposes mostly. Thank you.