Like The Boys, Invincible had a strong first season but diminishing returns with each subsequent one, with lots of cyclical narrative beats. There's not much depth or plot development going on, so it seems like the showrunners rely on graphic violence as a distraction. But when the show started off at maximum carnage, desensitization is inevitable. It was shocking when Nolan killed the Guardians, when Mark was eviscerated by Battle Beast and when Nolan and Mark fought. But there's nothing that can top those moments, and they were all in the first season, and it's been downhill ever since. It was intense the first time Mark got pulverized, or an entire city was leveled, but that happens almost every episode now. There was zero tension when the alternate Marks were wreaking havoc, despite the immense body count. The amount of times people have come back from what should've been fatal injuries, means violence has lost any weight or significance, and it was clear no one important was at risk.
The show has this weird dichotomy where it's both a traditional superhero tale and also plays against genre conventions (which is when it's at its best). I was close to writing off the show after the very first episode given how generic it felt. The only thing that made it interesting was the post credits scene. But when superheroics are played straight in the show it's pretty boring, which means that when all you have is subversion, then it becomes predictable and stale.
I'd still say the show is mostly fine, and certainly better than all of the MCU's small screen offerings, but it has the potential to be so much more. Invincible wants to have it both ways, the traditional superhero story where the hero lives in a world similar to ours and protects the status quo, and also have R-rated violence and language. The problem is that if superheroes really behaved like they do in the show, the story would more closely resemble something like Miracleman or Warren Ellis' Ruins. There's no logical consistency to the world of the show, and just like at the end of Man of Steel, the world basically resets after every global catastrophe, despite the tens of thousands of deaths. It's like the planet is in stasis, with superheroes having zero effect on geopolitics or the economy, which doesn't make any sense and undercuts the emotional resonance of the story.