Show what the laptop is under sync tabs for the desktop and vice versa. Hide or block any personal data. What OS? What Desktop? X11 or Wayland? I have no such issue seeing my other devices and their tabs under sync tabs. see screenshots

Thanks for the reply.

My devices are - A zoostorm desktop, Linux Mint xfce64, 22.1 Xia

   base: Ubuntu 24.04 noble, Firefox, all updated by Linux and all up to date (Linux manages the updates to the browser).

A Dell Latitude 7490 laptop, Linux Mint xfce64, 22.1 Xia

   base: Ubuntu 24.04 noble Firefox, all updated by Linux, all up to date.

An Android Samsung Galaxy A32, Firefox Mobile.

All logged in to the same Mozilla account. ALL DEVICES show up in the "Everything you are using and signed into" list in both the laptop and desktop firefox window for the Mozilla account and in the equivalent list in the Android firefox. All devices signed in and synced with the Mozilla account within the last few minutes. All devices set to sync "open tabs".

The Android firefox lists both the laptop and desktop as connected devices. I can't see how any menu or icon for showing me the open tabs on other devices.

Both the laptop and the desktop show ONLY the open tabs from the Android phone, in the drop down menu from clicking the Mozilla account icon in the toolbar.

The View-Sidebar-synced tabs option in both the desktop and the laptop firefox windows shows ONLY the open tabs from the android phone. It doesn't list any other devices.

I don't understand the questions about Wayland and X11. Here is the only section of my system info that mentions either/both.

Graphics:

 Device-1: AMD Renoir [Radeon RX Vega 6 ] driver: amdgpu v: kernel arch: GCN-5 pcie: speed: 8 GT/s
   lanes: 16 ports: active: HDMI-A-1 empty: DVI-D-1,HDMI-A-2 bus-ID: 30:00.0 chip-ID: 1002:1636
   class-ID: 0300 temp: 29.0 C
 Device-2: Microsoft LifeCam HD-3000 driver: snd-usb-audio,uvcvideo type: USB rev: 2.0
   speed: 480 Mb/s lanes: 1 bus-ID: 5-1:2 chip-ID: 045e:0779 class-ID: 0102
 Display: x11 server: X.Org v: 21.1.11 with: Xwayland v: 23.2.6 compositor: xfwm4 v: 4.18.0
   driver: X: loaded: amdgpu unloaded: fbdev,modesetting,vesa dri: radeonsi gpu: amdgpu
   display-ID: :0.0 screens: 1
 Screen-1: 0 s-res: 1920x1080 s-dpi: 96 s-size: 508x285mm (20.00x11.22") s-diag: 582mm (22.93")
 Monitor-1: HDMI-A-1 mapped: HDMI-A-0 model: HP 22xi serial: <filter> res: 1920x1080 hz: 60
   dpi: 102 size: 480x270mm (18.9x10.63") diag: 551mm (21.7") modes: max: 1920x1080 min: 720x400
 API: EGL v: 1.5 hw: drv: amd radeonsi platforms: device: 0 drv: radeonsi device: 1 drv: swrast
   gbm: drv: kms_swrast surfaceless: drv: radeonsi x11: drv: radeonsi inactive: wayland
 API: OpenGL v: 4.6 compat-v: 4.5 vendor: amd mesa v: 25.0.7-0ubuntu0.24.04.1 glx-v: 1.4
   direct-render: yes renderer: AMD Radeon Graphics (radeonsi renoir ACO DRM 3.57 6.8.0-71-generic)
   device-ID: 1002:1636

I hope that is all the info you needed.

this has me stumped.

The settings are set to share everything on laptop and desktop? see screenshot I would also try Dev, Beta, and Nightly to see what happens. I run all versions from my download folder plus Waterfox.

Thank you for the reply. All devices are set to share everything except history and addresses and credit cards, which I don't store anyway. They ARE all set to share open tabs.

As for trying nightly's etc. that's a bit beyond me.