This applies just to the people attacking others for headcannoning the character as trans, not those who don’t think Sakura is trans but have no problem with other people thinking they are
Personally I think the problem is, anytime a man likes anything cute, instead of calling it cute, they're called girly, which is a misogynist way of speaking that girly things are "less" than "manly" things, throughout this manga, nowhere it's mentioned that liking cute things doesn't make him any less manly and even cis-het guys can like them without getting called girly, so I absolutely don't mind if he just like cute things or actually wants to be a girl, just the usage of the word "girly" wasn't great, felt like stereotyping/degradation...does it make sense? I, as a kid, absolutely hated playing with cute and pink things cause they were called "girly", and the neighbourhood boys used to make fun of other girls; later I realised it's just toxic and insecure masculinity on their part. I don't need to like cute things as a woman, but I absolutely can (and I do sometimes), so dividing toys on gender terms is just stupid.
It’s insane to see so many people mad that a made up character might wanna be a girl instead of a boy just because you don’t want them to? Like yall are pulling out essays of “evidence” as to why Sakura can’t possibly be trans like there’s only one trans experience. It’s fine if you don’t take it as Sakura being trans, I personally didn’t think too hard about it, but it is disturbing that some of you are so bothered by the idea you need to write an essay defending Sakura’s manhood