Most writers are vibe-based more than anything, with consistency only being a thing that exists for the sake of the vibe. Homelander is stronger than Superman according to the show runner, because in his mind they occupy the same vibe of "World's strongest super-being" but Homelander has no morals:
His reasoning is non-sensical to (most) power scalers for example, but going from the writer's PoV the vibe seems correct. Homelander is an expy of Superman, if they were in the same story, he would indeed write their fight to go like that because Homelander is more ruthless as a person.
Mark and his crew lifting a city-sized spaceship is meant to be an awe-inspiring spectacle of strength, as if they fail millions of people are at risk of dying from the crash and explosions. They scream, put everything into it, and save the day. The vibe fits, it just makes every previous statement nonsensical since if Omniman can move meteors the size of Texas or shift planetary orbits, he should be able to stop the ship casually. Omniman struggles to kill a Bug, because it gives time for Oliver to show his dad that death isn't always the solution or option. Invincible gets clowned by random underground bugs because it allows the ReAnimen to be introduced, shown to be effective, and create a further rift between Mark and Cecil.
Ultimately, Invincible had a bunch of shifts in both purpose and tone. Originally, Kirkman wanted to make an early Image-style collaborative universe, but as time went on, he steadily started to dislike that idea and grew dissatisfied with the idea of his story being set in a never-ending universe. He'll randomly buff or nerf characters because that will fit the story better at the moment. I would like it to be more consistent, sure, but ultimately, most writers are just going off of whatever vibe works for the story. Omniman moving a planet isn't a strength feat necessarily; it's to show that he used to be someone capable of planetary genocide, but now hates that aspect of his history and is trying to make amends for it.
So when Kirkman writes that he hates power scalers, but also thinks Omniman beats Superman, those two ideas aren't mutually exclusive in my view. Kirkman's power scaling idea is that Twitter bros say Superman is Exaversal with Ludicrous FTL speed and can lift 8 biggatons. It's no longer taken as "the internal reference frame of a work's power structure" without clarification anymore imo.
Also, I've read works that are written by a power scaling like Shadversity's incredibly bad novel, Suggsverse works, and some really bad Xianxia novels. All of them are consistent in power scaling, but utterly cancerous to read because the important aspect (the narrative) gets shafted for cool explosions. Invincible being generally good story-wise with inconsistent power levels, is better than it having atomic precision power scaling with a bad narrative.