Google has recently started cracking down on usage of their Maps and Places data. If you use a Google Map or reviews plugin, this relies on Google's data.
What this means for you
You'll need to create what's called an API key (it's really just clicking a few buttons) in your Google account that gives the Wordpress reviews plugin permission to pull new reviews from Google as you get them.
Don't worry, most inspector sites will stay under their paid limits and will never have to pay for this service.
If you use a Google Map on your site, you'll need to enter this key into the dashboard of your site (we can help with this once you generate the key).