There are multiple problems with tab syncing on Android: - It seems like we don't sync tabs that are from pinned top sites. (maybe intended) - If no tab is open, we don't sync an empty list (which means on desktop the last open tab will appear this device..)
The pinned tab claim is strange, as the two shouldn't be connected in any way. Pins in Fennec are implemented as bookmarks which belong to a special folder. iirc, opening a tab from a pin isn't any different than opening a tab in any other way. What are you seeing specifically? As I'm testing this now, _none_ of my tabs are actually syncing :/
It seems that there's some "prior art" here.
Let's file and investigate any "pinned tab" issues separately, as the two are unlikely to be related.