Our senior developer Jarbas Horst has created a SharePoint Framework Extension which hides the Site Designs menu entry of all SharePoint site collections.
Site Design in SharePoint is a powerfull tool which has been available not just for administrators but for certain users since December 2018 as well, allowing these users to apply new Site Designs by themselves. At the moment it is not possible to disable the Site Designs or remove the Site Designs menu entry. For companies this can be problematic for various reasons.
On his blog, Jarbas takes a look at which users are able to see this menu entry at all and explains his SPFx Extension in detail.