Google is testing promoting the Google Maps app in the desktop interface of Google Maps.
Google is placing a little icon at the bottom left corner of the desktop interface that says "Mobile app." When you click on it, it takes you to an overlay that has links to the iOS or Android Google Maps app and a large QR to scan as well.
I cannot replicate this but it is showing up for Khushal Bherwani who shared these screenshots on X:
This is what you see when you click on it:
You'd think almost everyone with an iPhone has the Google Maps app and everyone with an Android phone has it as well, so I am not sure why Google feels they need to do this.
Forum discussion at X.