#92924 (comment)

This was a case where the product was not using invariant culture to parse a date.

It's probably worth having a look to see whether any unit tests throw up similar issues. We do run at least inner loop on es-ES in CI I believe. But I'm not sure this includes outerloop, and es-ES is sufficiently similar to en-US that it does not catch certain kinds of issues (eg., historically we've had several tests failed in Russian machine culture, and they were community reported)

suggestion: run all the unit tests including outer loop in a different culture, ideally with a different calendar, etc. or even a custom culture that is different to neutral culture in every respect -- calendar, date format, numeric specifier, etc. Every test should pass.

I've done this historically from time to time but I'll put this up for grabs this time

cc @filipnavara