Microsoft's Skype app is available in two different flavors on Windows devices: there's a desktop app you can download from the website, and a Microsoft Store app that's pre-installed with Windows 10. The two apps look almost the same, but there have been some significant differences between them, specifically the tighter integration with OS features that's offered by the Store app.
Now, though, Microsoft seems to be unifying the two apps, as a recent update to Skype Preview on the Microsoft Store has turned the app into the exact same thing you'd get with the desktop version, as first spotted by Aggiornamenti Lumia on Twitter. That means it's no longer based on React Native and it's using Electron instead, and it also means that a lot of the OS-level integration is now gone. That includes the ability to respond to messages from notifications or Windows 10-style incoming call notifications, as noted in a couple of tweets by another user, Florian B:
Yikes, just tried it & they obliterated every good thing the UWP still had.— Florian B (@flobo09) March 17, 2020
-No more people app integration
-No more sync with outlook
-No more automatic MSA sign in
-No more app pausing / working in background
-No more good looking title bar
There may be some benefits to using the desktop app instead of the Store app. For example, Skype 8.56 added the ability to easily quote a message using keyboard shortcuts, but the Microsoft Store version of the app didn't support it. Still, it seems like you may be losing more than winning here.
if you're not enrolled in the preview program for Skype, this change won't affect you just yet. If you do want to use the desktop app, though, you can download it from here, or join the preview from the Skype app settings on your PC and check for updates on the Microsoft Store.