People easily mistake neurodivergent speech patterns and communication styles for run-of-the-mill pretentiousness.
I don’t want to get too specific right now, but a lot of people who are neurodivergent (namely autistic, but there’s lots of overlap) struggle with communication. To them, writing/typing may be far easier and more natural than speaking aloud, but it can still come off as unusually formal, overly precise, or more awkwardly structured than usual. Sometimes it’s interpreted as “pretentiousness” because it doesn’t have the same casual cadence many neurotypical writers may use.
This is especially insidious because it can be an abuse response. Excessive formalism is a sign that I’m stressed and feeling threatened – I was taught growing up that people will pounce on the slightest ambiguity in anything I say to attack or blame me, so under threat I’ll do my best to nail everything down and avoid any possible misinterpretation. (It doesn’t really work, but it’s a habit now.)
To respond by attacking the formality itself is a special level of evil.