Some of these problems could be solved by having frontend validation on a number input. Regardless, I think the award for worst input goes to "datetime-local".

Some of these problems could be solved by having frontend validation on a number input. Regardless, I think the award for worst input goes to "datetime-local". The MDN page for it even says "Because of the limited browser support for datetime-local, and the variations in how the inputs work, it may currently still be best to use a framework or library to present these, or to use a custom input of your own". Followed by the date and time inputs, which are a real pain to work with.