This plugin is no reponsive?

It’s reponsive.
Why do you say it is not?

Please check it on your own: https://www.nasecestakolemsveta.cz/

Checked and it behaves unnaturally on your site.
Usually it is responsive but your theme is doing some strange stuff when it comes to CSS / HTML handling.
If you move the cookie notice div out of nobr element at the bottom of HTML output (footer probably) it becomes responsive again.

I suggest playing with CSS of your theme or asking the theme developer to work on it for you.

Thanks, will inform Theme developer.