When I'm logged out, and visit the top level of the site, the world map at the bottom of the page also displays briefly, and then is overlaid by the same gray "Oops!" screen.
"You must enable Billing on the Google Cloud Project at https://console.cloud.google.com/project/_/billing/enable Learn more at https://developers.google.com/maps/gmp-get-started"
I suspect either GFX didn't renew their map subscription, or it finally got hit by the Google Maps price hike of a year or so ago. (Basically, Google drastically lowered the number of "free" map views a site could get per time period, before having to pay for Google Maps.)
As far as I recall, this has started happening in the last week or so. It worked correctly semi-recently.