Personally I just hit Ctrl-W to close tabs when I get to somewhere I can't use it. `fixamo` and `set csp clobber` mean that I only really ever get trapped in PDFs (as I rarely open about: pages except to do a specific thing and then immediately close them).
I feel like this is a symptom of a larger issue: if Firefox is a GTK app (in Linux), why is it up to Firefox to decide how to resolve these inputs? Shouldn't it be GTK doing that? Ergo, shouldn't the "vi-ization" be occurring at the GTK level, and so apply to all GTK apps loaded by the user?
> They do not work in built-in pages (such as errors).
That's certainly dumb, though.
Otherwise, it's usually YouTube. I just only interact with the videos using the mouse (or MPV via `;v`) and make sure to click outside them afterwards.
I do have a trackpoint on all of my keyboards, so I don't really notice having to click the mouse because it's just another keyboard button, so I might not be the most representative person here.
Simply put, you cannot count on the keyboard shortcuts to work consistently throughout Firefox. They do not work in built-in pages (such as errors). They do not work when inside an input field in GTK. There's no way to consistently override built-in FF shortcuts that simply get in the way.
It's pretty sad for users which expect the keyboard experience to be consistent. I now mostly use FF's own shortcuts for most of the tab-management actions, since those are the only ones that work most of the time when an error page is generated.