April 2003 is when the iTunes Music Store launched: https://en.wikipedia.org/wiki/Music_streaming_service#Early_examples

The vast majority of digital release dates prior to April 2003 are fake dates (and nearly all dates prior to 1999 must be fake dates).

( At minimum, anything with a date prior to 1993 is fake data: https://en.wikipedia.org/wiki/Internet_Underground_Music_Archive )

Most of this fake data is seeded to the release editor by scripting tools, not entered by hand, so detection of this scenario would usually be instant.