Google killed off Chrome Apps. These were apps that ran in their Chrome browser but had access to things like USB ports. Okay, hardly anyone used them, but they were the standard method used to set up flight controllers for model quadcopters and planes - things like CleanFlight, BetaFlight and so on.
Apparently you can still download and run those apps if you have an actual Chromebook rather than just a Chrome browser - but you also need to know the URL as Google have removed the apps from its Chrome store.
What it means is that the guys who used to maintain and distribute those apps now have to maintain and support three different ones for Windows, Linux, and Apple - some are choosing to only support Windows, which is a pain for non Windows users.
It's just another of the long line of services introduced and then killed by Google.
One of those 'top ten services killed by Google' things - this one doesn't even mention Chrome Apps