I notice the same issue a few days ago with 109, but after a few days sync is now current. see screenshot You can also look at your sync tab and you'll see the same issue. This is why I run multiple browsers, just in case an update goes BOOM. Install waterfox or a previous version of firefox and you'll see all of your devices until 109 is current.

Thanks for that. I did notice a few days or a week ago that synced tabs from some devices were not showing on my iphone. Now I see that it has spread to the desktop. Let's hope this saorts itself out automatically as you say. I rely heavily on sync and sending tabs across devices.

It seems they don't come back on their own. I have to go to each missing computer and give it is kick. It seems just pressing the manual sync button doesn't do it either. Sending a tab from the missing computer to the computer where it is missing seems to do the trick (major pain though).

https://support.mozilla.org/en-US/questions/1403774#answer-1563909 This user had a similar issue and it took time for sync to... sync.  ;-)

I guess the missing device has to be on and has to push a new sync to show up. It's not enough to be a "connected device" on your sync mamagement page. I used to be able to send tabs to devices that were off, then when the device turned on, the tab would appear.

I guess the update wiped out the list of synced devices and they don't come back until you actually sync them.