We absolutely aren't using the black hole.
Completely ignoring how it'd be an exceptional outlier (like 5-C for it, yet 7-C attacks can puncture her defenses, 7-C attacks are noted to be impressive, pure raw mana expulsions from Sol, likened to just raw unfiltered power, only do 8-A to 7-C levels of damage, her older zoltracks explicitly not being capable of 7-C shit, etc wow almost like she's town level, coupled with a statement saying she can blow away a town too)
Even if we accepted it as canon, it'd be such a monumental outlier, that it'd be discarded anyway.
But as Dale has explained, it's anime only. Using the anime as supplementary is one thing, say a feat happens in both, and the anime just has more consistent shots, that is fine, it's still the same feat, the anime only helps us get a grasp on it. This is not that, this is a completely new and original feat, not even mentioned off-hand in the manga or implied it could be done, it's something wholely unique to the anime.
It's like, if you would, how Dio's eyesbeam in season 1 of JoJo is 7-C, yet in the manga all it did was slice a pillar, except worse because at least he did eyebeams in both while Frieren never once used a black hole in the manga or implied she could. Hell, in that case it'd be more like how Dio in the anime can turn into shadows and fade away, it's anime only, never happened in the manga, which much like Frieren, is what our profiles cover.
And to top it off? It ain't even Frieren who did the feat, it was a copy, aka, it'd be out of character for her to ever use.
Like best I can see is, when she gets a featbox (I plan on doing such a thing, mostly to cover the meme magic shit like paper airplane magic), that we give her a lil non-canon tab for it just to go "hey this happened, ain't that nifty?", and that's it, just for compilation sake, not even to use it.