> At the least, I expected there would at least be a way for me to say "trust me JS, this date is UTC so please parse it that way" - but the only way I could find to force that to happen was to manually add a "Z".

FWIW, I always use parseISO from date-fns for this. I agree it’s bonkers that this is necessary!

https://date-fns.org/v4.1.0/docs/parseISO