IDK if this is an unpopular opinion here or not, but:
I kinda think a lot of the time when people engage in fandom - They start to develop language to try and talk about things - But then eventually that language kinda takes over and becomes a mental prison - People talk within this very constrained mindset without realising things. I kinda cringe a bit at a lot of fandom discussions, because it kinda feels a lot of the time talking to someone whose more interested in a simulated construction of the thing than the thing itself.
I'm gonna list the examples from, how I see it, least controversial to most controversial
Canon: The argument for using this term is that you need an agreed upon consensus on what really happened in a fictional universe in order to inform future installments, which sure that's fine, but unless you've got a single writer who is very good, contradictions are going to happen, intents are going to clash - You see this a lot in media like Star Wars for example - You have lots of different writers and a lot of movies and comics and games and books and all sorts, so you're going to have cases where an earlier writer has a different view of something than a later one.
But a lot of people can't accept that - When they see a contradiction they're like "Well there must be a TRUE answer" - And so you get this weird appeal to authority developed, where there is a definitive source that goes like "The events of this piece of media are true, the events of this piece of media are false, here is the TRUE state of this fictional world" - But the thing is, that's made up, that's arbitrary, right? - None of this is real, none of it actually exists, it's fictional - The idea of there being a true state of a fictional universe is completely contradictory.
I partially get it - When it comes to fictional universes, you want to think of it as a cohesive world, you want to imagine these events bleeding into each other - But it's like, IDK, thinking some of these stories are "Canon" in the sense of they actually happened in these universe, and some are "Non-Canon" in the sense that they didn't happen just feels unecessary
Faction: This is one that I think has origins in Video Games, and has a lot to do with reputation systems, but really starts to bleed in to how people view worldbuilding in general(I'll talk about Worldbuilding later) - "Factions" has just become part of the accepted lingo of how people talk about Video Games, that you need to have groups with defined names and symbols and ideas and their own special outfits.
Here's the thing - How many times do you use the word "Faction" in real life? - Like, maybe you'll have a Political Party where one group is sabotaging the party as a whole to try and take power within the party structure, or maybe you'll have a civil war where groups aren't particularly easy to define, or you might have a segment of the military turn on another segment of the military during a coup - And you know those are what I'd call "Factions" - But that's such a tiny part of talking about the real world - But for some reason when people talk about Video Games, they believe this is like the core thing to write about.
IDK like let me give you an example: Let's say I'm playing Fallout 1 - Is Junktown a "Faction"? Is Killian and Gizmo's conflict a clash of "Factions", is The Hub a Faction, or are the Caravan Companies "Factions" - I'd say no, Junktown is a Town, Killian is a Mayor/Sherriff, and Gizmo is a slumlord with a bunch of goons, the Hub is a city, the Caravan Companies are part of the economy of that city.
IDK it's like, when engaging with media I prefer to think in terms of Towns, or Countries, or Cities, or Gangs, or Companies, try and think about what the group you're seeing actually is - the term "Faction" I feel conjures a very specific image of what a group is - And using it as the primary way to talk about conflicting groups in video games kinda destroys nuance.
Lore: I've come to be deeply suspicious of the term "Lore" because to me it's usually used for a Wiki Editor approach to media. The term "Lore" carries connotations of reading through ancient tomes, and of learning - But like, is that what media is? Do you learn about media or do you experience media?
IDK, for me how it feels to play a game, what a show or book or anything is trying to convey, are what's important. The idea that the default way of discussing media treats it as learning a series of disconnected facts is odd.
Worldbuilding: It seems to me that everyone wants to write the Silmarillion, whereas nobody wants to write the Hobbit - Everyone wants this big expansive mythology, nobody wants the small self-contained story one guy wrote for his kids where the details come from whatever he wanted that morning.
But the thing is - With a few notable exceptions(Morrowind, for example) - I think a lot of the things I like started off more Hobbit than Silmarillion.
You play Fallout 1 and there isn't this big expanded universe referencing constant events that happened outside of the scope of the story - You occasionally hear offhanded references to historical events, largely to make it feel more like an alive world - But most of what you learn about is directly relevant to the story you're currently playing.
Vault City didn't exist yet, New Reno didn't exist yet, the Vault Experiments didn't exist yet - They were writing for the game they were making, and sure the writers may have had discussions about other parts of the world or why the vaults are the way they are and those may have influenced later decisions - But things became true about the world as soon as they became relevant for the game that was being made - The world was built from the game, not the game from the world.
And from what I understand, the same is true of Star Wars, which is why you get weirdness like novels with completely different ideas of what the Clone Wars were, or abominations like the Holiday Special. Darth Vader being Luke's father, Leia being his sister, what the events of the Clone Wars were or how Anakin became Darth Vader, these are details that were fleshed out as the story was being developed.
IDK, I guess the wider point I'm getting at here is that, I'm a big believer that what matters is the text is the text itself, not the paratext. The world people actually get to explore and interact with matters a lot more than however many hundreds of pages of made up setting details you have.
I'd much rather play a game or watch a show where the writers are willing to rewrite details to fit better with the story they're currently telling, instead of staying consistent with a timeline and world that we haven't even seen yet.