Google Maps are not showing up in a signed apk
If you chose Google Play App Signing then your App's SHA-1 will be different one when it will be released.
Because Google remove your uploaded certificate and then sign the App with a new one,
So you have to know the new SHA-1 key.
(You don't have to follow the log for release and track the new SHA-1 generated)
You can compare the 2 SHA-1 keys.
Origin answer
I solved it by looking at https://play.google.com/console in the left menu configuration then integrity of the app and copy the SHA1 of the upload key certificate that is below the SHA1 Certificate of the app signing key and add it in the same api key of https://console.cloud.google.com/. This way I didn't have to make changes to the apk.
If it doesn't work for you add both and try.
It sounds like you only have the API key entered in the debug google_maps_api.xml. Also, it sounds like you're using the same API key for debug and release, but you still need to enter it in the google_maps_api.xml under the release folder as well as the one in the debug folder.
It's a little confusing, because when the project is in Android view, you can only see the debug file (although it should have (debug) in parenthesis next to it in that view).
In order to modify the release version, switch to Project view by using the dropdown in the upper left of the Project Explorer. Then, expand app/src/, and you will see subfolders debug and release. Under there, you should see two separate google_maps_api.xml files under debug/res/values and release/res/values.
Make sure that the API key is populated in the google_maps_api.xml file under the release/res/values folder, since this is the one that will be used for the signed release apk.
