Both cell phones are on Verizon and my iPhone X is running version 12.4 and the other one is an iPhone 6s on version 12.3.1.  Did you notice the differences in the code?

That thought crossed my mind as well but my Google Maps app was working fine.  I was able to fix it by going directly to Google and getting the code that way, so there appears to be something wrong with the code that Boldgrid is using to embed Google Maps.