Unfortunately, Google has removed call recording functionality in their new Android 11 developer preview! We sorry to get excited early and excite you along with us. We now learned (again) not to take anything related to Google as granted!
Go to https://developer.android.com/sdk/api_diff/r-dp4-incr/changes and click on Removals on the left to see removed "ACCESS_CALL_AUDIO" permission
In response to questions about call recording, Android product manager Matt-Pixel has said that:
Android has never officially supported call audio access. In some cases, apps were able to access this data through other means that are no longer available, due to changes we’ve made to make the Android platform more secure.
We recognize that this is a highly requested feature, however there are a number of privacy and security concerns that come along with providing APIs for this type of sensitive information. We have been working to determine if we can make these APIs available safely, and as some of you noticed, this capability was briefly available in an early Android 11 developer preview. Our intention is to continue investigating if we can safely implement this and we will update the Android community as this work progresses.