I'm facing a bewildering problem with Ctrl+Shift+T, which has only started in the past few hours and persisted through troubleshooting. In short, it's opening a default new tab when I press that combination, rather than reopening the last closed tab, as is its normal function. The problem is not that the tabs themselves are lost -- the "Reopen Closed Tab" drop-down menu entry is still available on right-click, and seems to function as expected. Similarly, I checked about:config to see if there was a problem with sessionstore or sessionrestore, both of which are at their default settings and can't be causing this. Rather, something about the combination itself is no longer working. I ran Firefox in Troubleshoot Mode to see if any of my settings were causing this. The problem persisted there, so that doesn't seem to be the case. A little over a month ago, I got a new phone and synced up my desktop and mobile (Android) Firefox tabs, which I hadn't done previously. This is really the only thing I can think of that would lead to any issues, but it's impossible to match the timeframes -- I noticed this problem today, five hours ago. (The failure for ctrl+shift+t to work includes tabs that were opened from mobile sync.) I make heavy use of this keyboard shortcut and would've noticed it earlier if it started earlier. Something about Ctrl+Shift+T itself is not properly being 'translated'. Ctrl+T works as expected (opens a blank tab), which is the same thing the Shift version is doing. Both my Ctrl and Shift keys are working fine in other respects (e.g. shift key capitalizes letters and adds special characters), so it's not keyboard hardware. It's not "inconsistent" -- it consistently works for everything else, and consistently doesn't work for this. I'm using Firefox 122.0 on Windows 11.