I always found it weird when systems code dates as DateTime strings. There needs to be a different primitive for Date, which is inherently timezone-less, and DateTime, which does require a timezone.

After having a bunch of problems with dealing with Dates coded as DateTime, I've begun coding dates as a Date primitive, and wrote functions for calculation between dates ensuring that timezone never creeps its way into it. If there is ever a DateTime string in a Date column in the database, it's impossible to know what the date was supposed to be unless you know you normalized it at some point on the way up.

Then I found that a lot of DatePicker libraries, despite being in "DATE" picker mode, will still append a local timezone to its value. So I had to write a sanitizer for stripping out the TZ before sending up to the server.

That said, I am pretty excited about Temporal, it'll still make other things easier.