To reproduce, run:

git clone https://github.com/gradle/santa-tracker-android.git
cd santa-tracker-android
git reset --hard origin/agp-3.6.0

// update gradle wrapper to 6.2.1
// update AGP to 4.1.0-dev

Running:

GRADLE_USER_HOME=tmp/ ./gradlew clean
GRADLE_USER_HOME=tmp/ ./gradlew assembleDebug
GRADLE_USER_HOME=tmp/ ./gradlew clean
GRADLE_USER_HOME=tmp/ ./gradlew assembleDebug

will fail with

* What went wrong:
Execution failed for task ':santa-tracker:checkDebugLibraries'.
> [:cityquiz, :dasherdancer] all package the same library [:dasherdancer].
  
  Multiple APKs packaging the same library can cause runtime errors.
  Placing each of the above libraries in its own dynamic feature and adding that
  feature as a dependency of modules requiring it will resolve this issue.
  Libraries that are always used together can be combined into a single feature
  module to be imported by their dependents. If a library is required by all
  feature modules it can be added to the base module instead.