Hamburger SVG Icon not found

So I have been using the mdbootstrap svg icon on my site and I have noticed that it has disappeared. I was using this line of code on my element:

background-image: url("https://mdbcdn.b-cdn.net/img/svg/hamburger6.svg?color=178E85");

I used this example page https://mdbootstrap.com/docs/jquery/navigation/hamburger-menu/

This page shows the same url values to the svg icons and it appears they are showing "Not Found" pages. This is the code snippet from the example page:

.navbar.navbar-1 .navbar-toggler-icon {
background-image: url('https://mdbcdn.b-cdn.net/img/svg/hamburger6.svg?color=000');
}
.navbar.navbar-2 .navbar-toggler-icon {
background-image: url('https://mdbcdn.b-cdn.net/img/svg/hamburger2.svg?color=fff');
}
.navbar.navbar-3 .navbar-toggler-icon {
background-image: url('https://mdbcdn.b-cdn.net/img/svg/hamburger1.svg?color=6a1b9a');
}
.navbar.navbar-4 .navbar-toggler-icon {
background-image: url('https://mdbcdn.b-cdn.net/img/svg/hamburger7.svg?color=BFE100');
}
.navbar.navbar-5 .navbar-toggler-icon {
background-image: url('https://mdbcdn.b-cdn.net/img/svg/hamburger5.svg?color=f3e5f5');
}
.navbar.navbar-6 .navbar-toggler-icon {
background-image: url('https://mdbcdn.b-cdn.net/img/svg/hamburger8.svg?color=E3005C');
}
.navbar.navbar-7 .navbar-toggler-icon {
background-image: url('https://mdbcdn.b-cdn.net/img/svg/hamburger9.svg?color=FF2C00');
}
.navbar.navbar-8 .navbar-toggler-icon {
background-image: url('https://mdbcdn.b-cdn.net/img/svg/hamburger4.svg?color=1729B0');
}
.navbar.navbar-9 .navbar-toggler-icon {
background-image: url('https://mdbcdn.b-cdn.net/img/svg/hamburger3.svg?color=00FBD8');
}

Have they all been removed?