Hello Guys! help me please…
I tried to make a login with otp firebase, over all my apps run well when export by APK … after uploading in google play, otp can not run … there is an error message phone failed… give me for information, help me please:D Thank you!
You have to do something to get your problem solved…
1 search on community
2 read this before creating a topic How to ask a question?
Are you enrolled for Google Play App Signing? If yes then your SHA1 key is changed, that could be the reason. You can get SHA1 of the key used to sign your apk from Play Console.
I have done everything … is there a problem in codular or on firebase?
watch this tutorial by Tech Guru India.
One important step is to get your SHA key in you google play console copied and paste it in your firebase before uploading it to play store to avoid this issue
Funny that the video popped up right after the solution was given in the community but nowhere does he mention where he got it from 
I just searched on YouTube and paste link here 
i even didnt watched full video, because in order to tell everything about that gonna be so long and i didnt know that is there any guide available so i posted video,
Mobile number must input along with country code.
Eg. India means +91XXXXXXX
that’s not a problem coz i set it like that previously. thank you anyway