Apex Legends Mirage buff arrived in the last patch major patch ahead of the release of Season 2, though developer Respawn Entertainment framed it as a bug fix rather than a straight-ahead buff.
Apex Legends Mirage Buff Included in Patch 1.2
Before Apex Legends Patch 1.2, Mirage's ultimate ability would deploy a mob of hologram version of Mirage and allow Mirage himself to sneak around using a sort of pseudo invisibility. That invisibility was nowhere close to perfect, however, and players frequently complained that their supposedly invisible Mirage maneuvers were being spotted too easily by enemies.
In Patch 1.2, Respawn Entertainment wrote in the patch notes that it had "fixed [a] bug where cloaked Mirage was too noticeable." Whether that effect truly was a bug and not a balance decision remains unknown.
Regardless, the new version of Mirage's ultimate allows him to become truly invisible, making it much more effective.
Photo courtesy of Respawn Entertainment/Electronic Arts