I notice whenever I highlight a paragraph, clicking the paragraph again doesn't de-select it, unlike every other program and webpage. I have to click outside of the paragraph to unhighlight it. As a compulsive highlighter who often double-clicks and then clicks paragraphs to highlight them and then unhighlight them, this is so bothering to me. (Also, if I click on a code snippet, a highlight appears to the left of it, and then gets left behind and doesn't reset when I click outside of the code snippet!) It feels like I've picked up an object and it was sticky and got residue left behind on my hands each time I interact with it. Sure, I could just stop repeatedly touching the object so much, but I fidget with what I'm holding. An object that's not fidgetable like every other of its kind is unnecessarily hostile. I'm baffled that a webpage went through extra work to make highlighting act differently and infuriatingly.
Highly related xkcd: https://xkcd.com/1271/, and highly related alt-text: "And if clicking on any word pops up a site-search for articles about that word, I will close all windows in a panic and never come back."