I’ll take you through the steps with screenshots. first open the add-ons menu in brave:
You can either pin DuckDuckGo to the top bar, or just click it here
That then gives you the popup menu:
Here you can turn off protection on the site.
Or you can open the settings (top right gear icon) and unprotected sites is at the bottom of the page where you can add dash.infinityfree.com
Obviously that is your choice, but the problem is the duckduckgo plugin, not infinity free in this case.