We have tried so hard for so many years for a proper date format. This is worse than Daylight "Savings" Time. We've been here before: https://xkcd.com/1179/
This is bad, but the worst is using Excel which is the biggest date-format-bully on the planet. "Hey that's some nice date strings you got there, shame if someone were to go and automatically reformat them on you. Oh, you've set your localization parameters, well guess who doesn't give a shit."
then when you manually change it to treat the cells like plain text, it converts the previously plain-text formatted date string into the internal numeric representation of the datetime