Developers will be able to submit the application for external testing through TestFlight 2000 testers.
Apple has also extended the application testing period to 2 months. Previously, the limit of external testers was 1000 people, and the testing period was limited to 1 month.
Only 25 people still have access to internal testing through TestFlight.
TestFlight is an Apple service that allows developers of applications for iOS, watchOS and tvOS to test preliminary versions of programs with the help of invited users and within their own team.
The service has been owned by Apple since the beginning of 2014.
A source: https://developer.apple.com