In a previous diff I removed jcenter() and replaced it with gradlePluginPortal() since jcenter() is (one day) going to be taken down and has been a source of issues in the past.
However... we're now experiencing issues with the Gradle Plugin Portal: https://status.gradle.com/incidents/9j9bx7nlwwf1
I wonder if adding jcenter() as a fallback will resolve things (at least in the short tun)