Referer being spelled wrong - I KNEW something was wrong about it every time I saw it but it never actually clicked.
That's why you spelled 'spelled': spelt :D
(Edit: or perhaps it's more about active/passive voice? Thinking particularly about burnt/burned.)
It's taken to an extreme by some thicker accented (dialected?) people around where I grew up though - an' so I turnt [turned] round (right-right round) an' said to 'im [...]!
UK native, upon seeing the word "color" thinks: "Aha, US spelling!"
US native, upon seeing the word "colour" thinks: "Aha, a typo!"
- readily available spell checkers
- the international interplay of ideas
The former stabilizes spelling, the latter says "screw it, through is spelled thru, I made up yeet, and emoji are valid grammar". But also grammar and spelling Nazis.
My money is on fluidity of language.