This reply is for review of dpi0 (addons.mozilla.org/en-GB/firefox/addon/most-recent-tab/reviews/2077913/).

The Most Recent Tab still works fine.
As for not remembering the shortcut customization:

(1)
There are 2 places to set up the shortcut for the Most Recent Tab:
[A] Extensions > Manage Extension Shortcuts > Most Recent Tabs > Main:
and
[B] Extensions > Most Recent Tabs > Options > Keyboard shortcut:

(2)
After setting up the shortcut in [A], the shortcut will be saved automatically, only at [A] will not overwrite at [B].
On the contrary: after setting up the shortcut in [B], we need to press Save to save; and then, this shortcut is also overwritten in [A].

(3)
And I think: the shortcut from [B] will always overwrite in [A], maybe right before Firefox exits or right after Firefox starts.

(4)
In short, you need to set up the shortcut in place [B], then press the Save button.

Works well! very pleased!!!! I like how you can click on the icon to go to the last window in addition to using a personalized keyboard shortcut.

FF 109.0.1 - This extension has worked for many years but today it has stopped working. Clicking the toolbar button (the way I like using it) to quickly switch between 2 tabs now does nothing.

Probably the best extension i have on firefox at the moment (as well as most underrated). Its a shame these extensions don't have more users as i think its one of the biggest time savers when it comes to over all user experience of the browser. Its simple, and it does what its supposed to. Seriously, amazing extension and its a shame it has only 340 users. Well done...

Super

I had problems with shortcut until I've found out the reason (Multi-Account Containers extension captured shortcuts, even though set to 'none'). The solution is here: https://github.com/mozilla/multi-account-containers/issues/1814 (go to about:addons, click on the gear in the top-right corner, click "Manage Extension Shortcuts", delete wrong shortcut assigment). Maybe you would like to add this hint to your option page?

Thanks for your extension, please fix error: can't switch tab after closing a tab.
Extension "Tab flip for Tree Style Tab" of "Mélanie Chauvel (ariasuni)" (https://addons.mozilla.org/en-US/firefox/addon/tab-flip-for-tree-style-tab/) works fine, but that extension does not support customize hotkey.

Simple, and just works!

This is fantastic! You should update the FF Add-Ons page; it still says "it's not currently possible to customize keyboard shortcuts" but v.2 of this Add-on does allow it. In reply to M., the "Ctrl+Tab cycles through tabs in recently used order" behavior would drive me crazy. This is completely different, and [Shift-]Ctrl-Tab still works as expected--in the visible order. Finally, a replacement for the old-style FLST add-on that was never updated to work with WebExtensions!

Awesome plugin, just what I needed except Firefox doesn't allow overriding of existing keyboard shortcuts. Because Firefox doesn't allow it, it renders the plugin pretty useless if I have to program it to some complicated shortcut that isn't used. I'm still going to be on Chrome and using with the "Alt + Q Switch Tabs Keyboard Shortcut" extension until Firefox fixes this. Switching to last tabs is essential for my browsing, so I won't be using Firefox until then. Great work to the developer of this plugin though.

Perfect!

Fantastic addition, even essential. So all that remains is looking forward for Firefox to finally implement proper shortcut management, a limitation I don't understand as many other browsers are providing it for years. And even though I am, thank God, not missing an arm or a hand, CTRL+SHFT+1 is unfortunately near unusable on a German keyboard. Not your fault, of course, and at least I have a button for now. Thanks.

Control-shift-1 is hard to use, can I use Alt-Q for the hot key?

Simple, does what it says.