We're currently using in 2.2 extra.less this type of code to change the node icons...
Which gives this result...

This isn't recognised by 2.3
I've tried the alternative suggested by @Jeremy P...
but it adds the fa icon but the SVG is still there...

I honestly think this is far too complicated and frankly I think it's poor that we're not offered a simple solution, or any solution.
So please, how to we fix this in 2.3??
CSS:
.node.node--id115.node--forum.node--read .node-icon i:before {
.m-faBase();
.m-faContent("\f164");
}
.node.node--id115.node--forum.node--unread .node-icon i:before {
.m-faBase();
.m-faContent("\f164");
font-weight: 900;
Which gives this result...

This isn't recognised by 2.3
I've tried the alternative suggested by @Jeremy P...
CSS:
.node.node--id(node_id) .node-icon i:before {
.m-faContent(@fa-var-download);
}
but it adds the fa icon but the SVG is still there...

I honestly think this is far too complicated and frankly I think it's poor that we're not offered a simple solution, or any solution.
So please, how to we fix this in 2.3??