Why is Google Maps API V.3 asking for an API key?

Question

Google Maps

Javascript API V.3 is connected to the project, according to the Google documentation in the third version, it is not necessary to register the API key.
All this worked for several months, and suddenly, when entering the maps, a warning began to fall out in the console:
Google Maps API warning: NoApiKeys https://developers.google.com/maps/documentation/j...
Moreover, it is impossible to determine which section of the code causes this warning ... there is no stack and it is not clear where the ears grow from.
How to understand what exactly causes this warning?

Answer 1

I have the same story - everything is fine on LAN, I put it on vp - this message pops up, did anyone decide?