The old logo is getting thrown out in lieu of what's basically the Copilot logo with "M365" added to the bottom-right corner. The app is also getting a name change, but you shouldn't get too ...
The logo is pretty much identical to the standard Copilot one, albeit there's a teeny-tiny "M365" marker at the bottom right. If you haven't noticed the marker, there's a good chance you're using ...