Header Image issue in Firefox

Hi Team, We've recently encountered an issue with our header images not displaying in Firefox and Safari. It works in Chrome and Opera from the testing I've done. While inspecting the source, the image paths are different. In chrome, it's https and in firefox it's just http. Any idea on why Firefox doesn't have http as the image link?   Website: http://waimairitoylibrary.org.nz/ Header image link in Chrome: https://abf875.a2cdn1.secureserver.net/wp-content/uploads/2020/08/header-011.jpg?time=1670368012 Header image link in Firefox: http://abf875.a2cdn1.secureserver.net/wp-content/uploads/2020/08/header-011.jpg?time=1670368012 Any assistance you can provide in helping us fix this would be greatly appreciated. Kind regards, Nathan