Recently I have spotted a test that Google is doing that prominently displays how long a business has been open:
This is something I have only spotted a few times so it is something Google is testing and is not fully rolled out.
Google is taking this from the opening date inside the GMB dashboard:
Something else I noticed was that if the business hasn’t filled out this field in the Google My Business dashboard, Google is defaulting to showing that the business has been open for less than a year, like they are doing for Lawn Patrol here.
This is clearly not ideal, so I would suggest making sure you have this field filled out in your dashboard just in case Google decides to roll this out to everyone.