forms: How to silently avoid web forms spam (specific names, email addresses)?

I am using Webform in Drupal 8; I have some spambots that fill out exactly the same form every day.

I want to do some kind of validation that automatically blocks these publications. For example, if the given name is "Spambot 1", I want to discard the web form submission automatically.

Drupal 7 has the Validation of web forms module but this has not yet been ported to Drupal 8.

I found a snippet of code when adding a custom validation to a web form element, but this seems to be to provide useful errors that allow the user to re-submit the web form, while I want to make it appear that the form was sent but discarded in Submission silence.