A
Amaris
Guest
I would have liked it if we found out, in his background, that he was considered slightly below average in terms of capability, and ended up overcoming that to excel as one of the Federation's greatest physicians.Easily this. Like the revelations about The Sisko's parentage in the final season, it takes a credible (very real, very flawed, very human) character and taints them with a backstory that retroactively makes their achievements in overcoming the adversities of their life, as well as all of the character development we've seen them undergo on-screen, seem..... a little less impressive, to be honest.
I've seen some people claim that bringing Alexander back was a bit of a misfire too, but I actually kind of liked what they did with him. Felt like a nice progression from his last TNG appearance, and gave the Worf/Alexander relationship a new aspect.