In Apex Legends, Mirage's decoy is merely meant to distract and confuse enemy players. Instead, it appears that the decoy tactical ability of the character is actually blocking some damage, which isn't what Respawn had intended. Thankfully, Respawn is on the case to fix it.
Over on the Apex Legends subreddit, a video showing a player experimenting with Mirage's decoy has emerged. In the video below, the player demonstrates that the decoy can block incoming grenade damage.
Further down the comments, a Respawn dev has noticed the issue. "Thanks for letting us know! I've made a report," the dev wrote, meaning Respawn will hopefully be fixing the issue soon.
I don't know about you, but this comes as a bit of a surprise to me. I've always sort of assumed that Mirage's decoys could block incoming damage, but it makes perfect sense that holographic projections shouldn't actually be able to block explosions and bullets.