Google Play App Signing
In case you are using the app signing feature of google play store, when you upload your release build to the google play store, it assigns a new SHA1 fingerprint to your app - which might lead to UNAUTHORISED_PARTNER_KEY error for your app, since the appKey used by you in your app config was generated for a different SHA1, and hence won't work for the new SHA1.
In this scenario, you need to go to the "app integrity section" of the Google play console, where you would see 2 SHA1 keys (a) Upload Certificate SHA1 and (b) App Signing Certificate SHA1.
You need to note down the "App Signing Certificate SHA1" from the console, and generate a new Truecaller partner key ( app key ) for your play store build. Configure this key for your play store build in your project, and upload the build on play store for your users