The G Suite device policy will restrict non-critical app use for anyone who is using their own personal device for corporate purposes. The advent of Google's apps for work program and the improvements that Google has made to it over the years have made it possible and a lot easier for corporate employees to bring their own devices in to use in place of a corporate-issued device. That said Google has always done its part to try and make sure that devices are as secure as they can be so that no sensitive information is leaked or put at risk, and this is the latest change that Google is making to work towards keeping that security.
In a post today on the G Suite Updates blog, Google notes that while the Google Apps Device Policy has always been there to help keep things secure, it will now only allow people to use the work-related apps that are critical the workplace environment. You can see a sample of what that looks like below but essentially if you have certain work apps installed on your own personal device and the Google App Device Policy is enabled, the Google App Device Policy will alert you if it ever notices that your device has somehow violated the security policy. The Device Policy will then deem the device as non-compliant and lock any non-critical work-related apps down.
In the second screenshot below you can see how this looks. In the work folder with all of the employee's work-related apps which contain files and data sensitive to that workplace, all of them are grayed out with tiny padlock badges in the corner to display that these are no longer usable. The good news is that the Device Policy will remove the restriction on the use of these apps once the security policy violation is taken care of and the non-compliant device is deemed compliant again. For businesses who use Google Apps for Work, Google says that the feature is being pushed out to G Suite apps in both rapid release and scheduled release tracks, though it does state that it could take up to 15 days for all users to see the features available in the apps.