The Plugin "Cookie Consent" generate following HTML <a href="#" class="cncb-js-restore">Hier können Sie Ihre Zustimmung zu Cookies widerrufen.</a> from the shortcode [revoke_consent text="Hier können Sie Ihre Zustimmung zu Cookies widerrufen."].
(As already said) With content filter we can put the shortcode in the text, we can also change some stlying like background-color (for some reason not text) via custom CSS oh the consent plugin or in the WP customizer.
a.cncb-js-restore {
color: #ffffff;
background-color: #f7eb5b;
}
But it also went out that the shortcode is displayed, but it have no functionality no mater if "Smart Loading for HTML- und Shortcode-Elemente" activated or not.
In the end we pasted a result of the shortcode instead of the shortcode itself in the page, also <a href="#" class="cncb-js-restore">Hier können Sie Ihre Zustimmung zu Cookies widerrufen.</a> So it works now like this, although the text is still black, it is legible thanks to a different CI background colour for it now.