I had a custom new tab page working in Firefox on Arch Linux before I had to reformat due to various reasons and wanted to start new since I was changing my workflow from minimal no DE, no display manager, bspwm to Plasma 5 and SDDM etc.

My custom start page used to work for both new window and new tab, but I must have missed writing down a step because on this try, it’s only working for new tab and not new window.

Original post was on Reddit, but since the sub went private, I can’t access it.