REG-EX on the contact form fields

Hi Nicepage team,
I recently recognized a "Kazimir" (kind a "waste-all" person) in my nearby, and he is posting from my and my client's website using my own personal email address. That's why, I would like to ask, what happened with the Regular Expression option, which is no longer visible neither in Desktop application, nor in the edit of the contact form in the web editor.
In my case, I would like to use for the email input field a regex, so the resulting rendered HTML would look like this:

<input type="email" pattern="^(?!john\.doe@yahoo\.com$)(?!.*@([a-zA-Z0-9.-]+\.)?mydomain\.online$)[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$" title="Email address not allowed.">

Any chance to make it available again? As some time ago, it was possible to use the regex in the form.

Thanks in advance,
Michal