I recently started seeing the same behavior on Firefox 122.0 (64-bit) - Linux. I set the time to 1 minute, the timer on all tabs count down to about 0:55, then it is reset to 1:01.

This is a recent behavior change.

I'm also experiencing this behavior, using Firefox 115.7.0esr (64-bit) on Debian. I'll add that it seems to only happen while the browser instance is focused (so a separate window of the browser will continue to countdown while not in focus).

Anyone have an idea what could cause the timer to restart outside of switching to a tab?

Hi, developer here. The timers will reset every 5s if you have fewer than your minimum number of tabs open (this is entirely unapparent, the UI should make that obvious). The minimum number of tabs setting is currently per browser window, a feature I have begun to change but have not finished.

Wow, I feel pretty dumb. Thanks @ssorallen

I've always had the "Auto close only if I have more than..." option set to 5, but somehow managed to change to 20. Didn't even think to look 🤦 Seems to be working fine now.

@jacobflanagan No no, you are definitely not dumb. Tab Wrangler has many crummy bits like that, the fault lies in Tab Wrangler's UX and poor feature descriptions.

This has been a side project of mine for a number of years, and there is always more to do. Always happy to accept pull requests from folks. Suggestions and bugs are helpful as well, but my desire to work on them comes and goes since this is only a hobby for me.

Closing - feature is working as intended, there were fewer than minimum number of tabs open.