There’s a whole genre of sci-fi that has a major premise as “humanity is the most powerful/dominating/victorious species in the cosmos…and that’s not a compliment”. I always understood that to be a facet of HFY, but per this sub’s description HFY should be “uplifting”.
Like, a story where aliens try to invade Earth and we kick their asses is definitely HFY. But what if we then enslave the survivors of the alien horde? What if we reverse engineer their tech, go to their homeworld, and nuke their planet? What if we tailor a virus to their genome and purge the galaxy of their entire species, and their little alien babies die screaming in their little alien cribs?
Is that HFY?
A really good example of this is when humans decide in Adrian Tchaikovsky’s “Children of Time”
SPOILER
to extinct an entire civilization made from uplifted spiders because they have the audacity to inhabit the planet the humans want to colonize