Contact Form Submit button has empty class

Hello,

I have a contact form here: https://www.vztplzen.cz/kontaktni-formular/ It is built using Elementor’s Contact Form widget. The submit button has empty class:

<button type="submit" name="submit" value="submit-contact-b1e59dc" class="">ODESLAT ZPRáVU</button>

How can I assign a class to the element? My clients needs that for some GA/GTM magic. I can’t find it anywhere in the settings and I didn’t manage to find any documentation on it.

I tried disabling a CSS/JS minification plugin, clearing the cache and regenerating Elementor’s CSS, but neither helped.

Thank you.

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