Custom field date timezone bug

When creating a custom field of type “date,” values entered there appear to be saved using the epoch format equivalent of 12 AM on the specified date in GMT. If the WordPress site is configured to use a different timezone (e.g. US Eastern), this does not seem to be accounted for in subsequent display of that date value; the date then incorrectly displays as the day before the intended value.

Notably and critically, this includes when the date value is loaded into that custom field upon next edit of the contact record. One possible result, then, is that every time someone saves the contact record, the date value is incorrectly decreased by one day, even if the value is not touched by the user in their editing. I think this makes custom date fields unusable as-is.

Here’s a video of this bug in action: