1. Using the packageName extracted from the AndroidManifest.xml,

2. You shold remove package form AndroidManifest.xml file.

3. Add a namespace property under the android block in the build.gradle file.

Like this:

// build.gradle 

android {
    namespace "packageName"
    ...
}

See detail : https://discuss.gradle.org/t/namespace-not-specified-for-agp-8-0-0/45850