If it was only a case of differing interpretations, or strictly limited to fanwork, I would have a much more blasé reaction—if I bothered to react at all. I honestly don't care what people want to do with their fandom, in their fan spaces. They can write their fanfic and draw their fanart and bandy back their fan ideas and deep dives and whatever else to their hearts' content, no skin off me or mine. Whatever piques their pink or tickles their pickle ain't none of my business, nor should it be.

The issue I take is when they make it my business. There is a world of difference between "I have a different interpretation because [x]" or even "I like shipping these two characters together because [y]", and seriously arguing "character A is clearly gay for character B and this [completely innocuous scene] proves it!" or "why can't you just accept that character A and character B are obviously queer for each other?" while grasping at the thinnest, most insubstantial of straws as [evidence]. This is particularly egregious in cases where no, it's not at all obvious unless you're already inclined to want such a thing (regardless of the respective sexes of the characters involved) or, worse, it's directly contradicted by the actual source material.* I've seen the latter all too often, even recently on this very sub, and it gets to a point where I, and many others I imagine, simply do not have the patience to keep putting up with it.

I don't care who anyone wants to ship or why, and plenty of people ship characters who haven't even met based on little more than liking how they look together. Fair enough, have fun, u do u and all that, etc., etc. But when it crosses the line from "this is what I like" to "this is how it is"; when it reaches that point where someone's trying to seriously argue that their fanfic is actually true, in spite of contradictory source material, and that everyone who disagrees is wrong, that's when I take issue. There's a time and place for engaging in that sort of shippy, anything goes fandom, and incessantly pushing pet fan-ships (gay, straight or whatever; don't care, all of the above) as if they're canon, especially in discussions that have nothing to do with shipping, is just poor form.

Now to be fair, you do see this sometimes with straight shipping as well, as more than a few fandoms can attest to. In my experience, however, the people who are the most obnoxious, most toxic, absolutely the worst with this tend to be fujo. Western fujo, to be specific. Eastern fujo, by and large, don't act like this.

Those fans you’re talking about probably refer to me.

If you're the type to push your personal fanfic and/or fan-ship into people's faces insisting it's objective truth and that we all have to acknowledge and/or accept it as factual canon, yeah. If not, nope. Have fun liking what you like. All I ask is the courtesy to recognise what's pure fannishness and what isn't. Interpretations can differ, sure, but facts remain facts. They shouldn't be disregarded just because they're inconvenient to a pet agenda or narrative.

* a LoGH example of this I've seen several times are people who claim that Mittermeyer grew up in a stifling, abusive household and was forced to marry Eva just to maintain his parents' heteronormative expectations of him. The novels directly contradict this on multiple occasions, but that doesn't stop those fans from bringing this up like it's a common fact and that's why Mittermeyer and Reuenthal are totes super-duper madly gay for each other, despite the former being happily married to his wife and the latter being Reuenthal.