validation for date fields?

I have a standard "date" field (without time) and it seems to expect the date to be in the format YYYY-MM-DD. If a date is entered with the keyboard and it is not the mentioned format the date is replaced with today when the form is saved but there is no validation, warning or error. How can this be captured and thrown back to the user?

Is it possible to change the expected format? Or is it possible to show the expected format as a default text?

thanks for your time!

Hello

the change is done via calendar JS when you click submit and not when the data are validated on server

Yes we could add adding configuration for customizing this
because the Joomla calendar supports defining custom formats

but

we first for proper UX,
we should add a placeholder to the input field to indicate or display the placeholder as a tip text to the side

YYYY-MM-DD

which will be a language string so that it is translatable

thanks for your answer. A placeholder text with the correct format sounds a good first step.

But some kind of validation is also required to prevent accidentally submitting wrong data. Currently you can enter anything (even garbage text) and it will get replaced by today's date. The default behavior should be to verify against the required format and prevent any submission with a wrong date format.

Do you consider implementing something like that? Do you have any other solution other then preventing text input as a whole?