Gamers are unable to purchase the Dead or Alive Collaboration DLC for Senran Kagura Estival Versus because the Dead or Alive Distribution License issued to XSEED Games by Koei Tecmo expired in March 2021. And XSEED Games only gave people a 2 days notice before the DLC was removed.

If things stay the same then the Collaboration DLC will be lost to time and people will continue to hack and pirate the game just to play as Ayane.

Yes that is correct. That's how badly people want this Ayane DLC. They're willing to hack and pirate the game just so they can play as the character. People are risking getting their accounts banned just because they want the character back. And at the moment that's the only method that new fans can play as Ayane until Koei Tecmo renews the License for XSEED Games.