Should this be a 130 fight? It's significantly harder than everything else in the 125 block and I think she has way too much health. For instance, ony my Cold Wolf this season it takes me ~30 seconds to kill Innarius in The Void (130) at level 130, and ~2 minutes to kill the Ascended Riftwalker (130) in Invasion III at level 130, but over 6 minutes to kill Atanna Khan (125) at level 133.
I don't think it's implicitly bad to have certain fights designed to be longer -- Spirit World for instance can be pretty long, and while I think the RNG of the invulnerable nests' spawn location and frequency should be toned down, for the most part that fight feels very good and it is usually around 5 minutes. But Atanna Khan just feels so much more like an HP sponge, compared to Spirit World having lots of mechanical maintenance.
If Atanna Khan is going to stay a 125 fight, I think she should have a lot less health. Even if this was a 130 fight, she still would have too much health compared to the other fights in her bracket. I know some of the extra time is because she is pretty anti-melee with her constant teleporting away and area denial -- but even accounting for that, it seems like she has way too much health.