Mirrors are a dual sided debate. Some say mirrors will make a bird aggressive and some say they will be entertained or even think there is a buddy around. Birds are smart so I don’t really buy the buddy argument but I have seen videos where birds go nuts. Some think they have a buddy and some get territorial. Just keep that aggressive point in mind when experimenting with mirrors. If your bird is accepting of it, great. If not, eliminate mirrors from the bird’s environment.
If you notice that adding a mirror all of a sudden makes your bird aggressive towards you, remove it. Also, since birds are creatures of pattern like all animals, take note of changing things in the environment be it a new job with different hours or more stress or changing the color of the couch. These things can affect bird behavior. Its mundane to us but it can be a big deal to a bird. When I was 4 my grandma went blonde and apparently that saddened me to no end. Birds are winged toddlers. Be mindful of the small things because they may be small to us but huge to your bird.