https://en.wikipedia.org/wiki/Business_Source_License:

  Debian FSG compatible No
  FSF approved          No
  OSI approved          No
  GPL compatible        No
  Copyleft              No

I'm sorry - what I meant to say is that it is listed in the SPDX (https://spdx.org/licenses/BUSL-1.1.html) as a recognized license. The revenue gate means it will never be considered an open-source license by the OSI.