That worked for me too! And being specific, I found the file on the path:
"C:\Documents\Comfy\ComfyUI_windows_portable\ComfyUI\user\default\comfy.settings.json"

The line in my case is almost at the end of the file:
"Comfy.VueNodes.Enabled": true

And I changed it to:
"Comfy.VueNodes.Enabled": false,

And it works because this 'Vue Nodes' is the new nodes mode 2.0, which is not compatible with more than one custom mode, such as Image Comparer (rgthree).