Running Firefox 140.3.1 ESR on Debian, lately I've been experiencing a bug when I have several instances of Firefox open, and multiple tabs open in each instance. After a few minutes of browsing and opening and closing tabs, I am unable to drag tabs to rearrange them (above the address bar). The "X" that is part of the tab also doesn't work to close the tab, and clicking the main "hamburger" menu icon (three horizontal lines) does not drop down the menu. If I switch to a different instance of Firefox that is already running, sometimes the "hamburger" menu icon starts working (sometimes not), and I am able to exit and restart Firefox, which works for awhile, and then a few minutes later the same thing happens again. Interestingly, when it's not working, I am still able to "right-click" on the tab and choose "close tab" from the drop-down menu. I've been trying to discern a pattern, but have not been able to find a way to reliably reproduce the error. It often seems to happen when I'm using Reddit or Craigslist (maybe only more noticable because I often open and close a lot of tabs on those two sites). At one point I thought it might be related to opening a new tab for a site that had previously been opened in another Firefox window (instance), but that may be a false lead, because I haven't been able to find a way to consistently trigger the bug. Thank you for maintaining the best privacy-respecting browser in the world, an indispensable tool for me.