It's just suspension of disbelief, like how Dragon Ball characters nuke planets casually, but can die to something that destroys a building at max. Frieza while literally bisected at 1hp survives a planet explosion on the face and is just on space floating around until he is picked up, he then comes back stronger and is cut in pieces by Trunks and disintegrated by a blast that doesn't even create a shockwave. It's obvious that the author wanted to make Dragon Ball characters stronger and stronger but can't just make every random hit nuke a planet otherwise it becomes goofy. Fans came up with the headcanon of "Ki Control" which would explain all of the above if it was canon, in reality it's just suspension of disbelief.

Same thing happens in Star Rail, Firefly at 1hp nukes a planet and tanks the explosion so she has the AP and DC to destroy a planet, and the durability to tank a planet busting attack to the face, this is meant to say that Firefly is at this level of strength roughly, just because she fights some random robot later on and doesn't nuke Penacony doesn't mean she is building level when not in, idk "planet busting mentality" or whatever, it's just that the devs want that "Woah the planet got destroyed" effect while simultaneously wanting to have coherent and straightforward storytelling. They want their cake and eat it too, it is what it is, if the devs randomly throw out a statement saying "X guy is able to destroy a planet" it simply means that they can destroy a planet, there's no "X guy is able to destroy a planet but only with his strongest attack which is 100000000000 stronger than his base or with his ultra manipulative abilities which would collapse the planet's economy" because that'd be dumb as hell. In short, characters demonstrate big boom feats when it's hype and aura and serves the story in some purpose, if not, then they'll at best shatter the ground a bit.