Robert Basic has a quick post to his site sharing a method he uses for creating datetimes from a format with a timezone. In his examples, he makes use of the createFromFormat handling in PHP's DateTime functionality to more correctly handle processing strings with timezone offsets rather than a DateTimezone parameter.

I wouldn’t be writing this blog post if I’d read all the “fineprints” in the PHP manual. Alas, here we are.

The DateTime and DateTimeImmutable classes have a createFromFormat method. As you can probably guess from its name, it creates a datetime object from a datetime string formatted in the specified format. [...] When the format has a timezone offset though, that’s… the part I skipped in the manual.

He found that the createFromFormat handling ignores the provided timezone as the optional third parameter if there's an offset included with the date/time string to parse. No error is thrown, it just silently ignores the third parameter and sets the "timezone" value of the resulting object to an odd value.