The windows 11 teams runs better, but if you're using a school or work account, you need to use the old AngularJS+Electron version, or the new React+Webview2 version.
So for the time being, the Windows 11 teams is more catered for personal use only. It's kind of like a modern reboot of Microsoft's old MSN Messenger. It was included in Windows 11 (rebranded as "Chat") but it's been unbundled from Windows 11 installs and I think rebranded again. But not having the school/work account support means not a lot of people use it.
The transition between the AngularJS+Electron version and the React+Webview2 versions is happening now. At some point soon, anyone who is running an OS too old to run the new teams will be forced to use the browser version.
So after their transition, we'll have to wait and see if they add the school/work account support to the native version because everyone using teams right now only uses those accounts.
even though it's borrowed some things from the jpeg-xl encoder, it's still not as good as actually using jpeg-xl