No service despite coverage map saying so

I live in the Charleston South Carolina area and the 5G map is dark green for a couple of hours and either direction.

Incredibly frustrating experience today trying to do door dash. On Google fi I had no problems, but today anytime I moved outside the immediate Charleston area it would go completely no service until I return to the city.

So I'd pick up an order in town, drive out a little bit and it would drop and then suddenly I couldn't find the customer's address or get new orders.

Has anyone else had coverage on the map but still had Network issues?