Google blocked all third-party call recording apps from working with the Android 9.0 Pie update. Since then, it has been up to OEMs to add the call recording feature to the phone app in their devices. Since Google itself has not added call recording support to its Phone app, all devices that ship with the app as the default dialer app miss out on the feature as well. This includes Google's own Pixel devices, all Android One devices from Nokia, Xiaomi's handsets sold in the EU, and more.
A teardown of the Google Phone app from January this year had pointed to the company working on adding native call recording feature to its app. Now, it looks like Nokia and Google have started rolling out the call recording feature in the Google Phone app for select Nokia devices in India, with users of Nokia 7 Plus, Nokia 7.2, and Nokia 8.1 reporting that they have got the feature on their phone.
It is unclear how the call recording feature was activated on these phones -- via a recent software update or a server-side change. References to the call recording feature were also found in the recent release of Google Phone v47, but there have not been any user reports of the feature being enabled on non-Nokia devices post the update. Considering these reports, it is likely that Google will soon roll out call recording to its Phone app as well.
Source: XDA Developers