I just tested making a website with the Joomla tool (necessary software to get a website working not the domain) but don’t know what they used to make the forum, after searching a little bit I found something similar on a plugin for WordPress called Woocomerce:
If they’re using it, supposedly can be disabled on:
Admin > Woocommerce > Settings > General > Store Notice
Just noticed it also appears on the bottom part of the website:
This reply was modified 2 years, 5 months ago by larioxem. Reason: Adding a picture about the bug