Exactly! But its not obvios. So most of those shitty websites don't even know they have a problem.

Then there are also people ignoring it on purpose. I once read a reddit comment saying 'well of your address looks like "John wick 🐶❤️"@2001:0db8:85a3:0000:0000:8a2e:0370:7334 I don't event want your email in my DB because oit will break something

That's one very random place to find that. There are a lot of different one and there is no way we all just agree to use that one.

Look art his site that shows a more complete and (in theory) official website. While also explaining that there is no regex that is perfect

https://emailregex.com/

(Compete regex for the lazy)

(?:\[a-z0-9!#$%&'\*+/=?^\_\`{|}\~-]+(?:\\.\[a-z0-9!#$%&'\*+/=?^\_\`{|}\~-]+)\*|"(?:\[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\\\\[\x01-\x09\x0b\x0c\x0e-\x7f])\*")@(?:(?:\[a-z0-9]\(?:\[a-z0-9-]\*\[a-z0-9])?\\.)+\[a-z0-9]\(?:\[a-z0-9-]\*\[a-z0-9])?|\\\[(?:(?:25\[0-5]|2\[0-4]\[0-9]|\[01]?\[0-9]\[0-9]?)\\.){3}(?:25\[0-5]|2\[0-4]\[0-9]|\[01]?\[0-9]\[0-9]?|\[a-z0-9-]\*\[a-z0-9]:(?:\[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\\\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\\])