Losing my mind on this one. Have 2 Macs I use at home, both running FF 141.0 and Sequoia 15.5. Use Reader for RSS and Airmail for eMail. Both have settings to allow links clicked in those programs to open browser tabs in background. Handy way of banging through newsletters and RSS feeds before shifting to browser. One on Mac, that open in battleground setting on both apps works as it has for, oh, last several years. On the other Mac, a few days ago that open in background stopped working with Firefox. It does work properly on Chrome and Safari if I set them as default browser (and, as I mentioned above, on my other Mac). I've tried resetting Firefox on this Mac using the troubleshooting menu and have also cleared the Firefox cache. I even tried resetting the launch database in that Mac, although the fact Chrome and Safari are working fine suggests the OS isn't the culprit. I'm unaware of having changed any settings, but am aware that "idiot user" may be the issue. Regardless of how this happened, any ideas how to sort this annoyance out? Thanks!