The concept of glorification is one that I wasn't really able to pin down until recently. But it's super important in fiction writing. It's similar to the concept of a moral. The amount of "glory" you give to a character is very important, because it influences how the reader thinks of them, and by extension it can be used to create a moral (whether on purpose or not) - if a certain member of Team Good is always the one to suggest the right plan and point out the flaws in everyone else's ideas, never loses or fails at anything, and is always brave, etc, then your story is pushing the idea that this character's ideology is right. Like with other sorts of morals, this can be used for good, provided you do it carefully - don't get too pushy with it or readers that disagree will be turned off by your "preaching".

Besides that, if you've done a good job creating likable characters, readers will likely get very attached to their favorite ones and be offended when those characters are de-glorified. The Doki Doki Literature Club fanbase is an excellent example of this phenomenon. That's because Doki Doki Literature Club is an excellent example of how to create lovable characters. And no it's not because it's a romance game (it isn't) and the girls are specifically designed to look as cute as possible, I swear if you think that you haven't played the game.

So, how do you glorify characters? I think there are three main things that contribute: competence, agency, and maturity. I've talked about agency in other articles, so maturity is the only one that really needs explanation. Maturity in this context is a rather broad personality trait that seems to be composed of several Protagonistic virtues: Stoicism, Diligence, Objectivity, and Serenity, mainly. So when you have your character complain unreasonably about a small hardship, act entitled, or respond to kindess with some rude and ungrateful comment because they can't handle the thought of having their status lowered, you're de-glorifying that character.

Summary: it's important to pay attention to how much glory you're giving each character. If you give a character more than they deserve, readers who dislike the legitimate flaws of that character will get annoyed, and if you don't give them enough, readers who like the legitimate virtues of that character will get offended.