I have recently been experimenting with syncing tabs on my three devices. On two less-secure devices, I have everything synced, and on one more-secure device, I have nothing synced with the other two. However, I would still like to be able to share tabs with the less-secure devices in the chain.
Thus, my suggestion is to enable sending tabs and receiving tabs in the sync settings separately. Enabling syncing “Open tabs” will enable sending tabs by default (through the context menu option or however else it is typically done), and enabling “Receiving tabs” separately will let that Brave instance receive tabs from any other instance with “Open tabs” enabled, regardless of whether or not the other instance also has “Receiving tabs” enabled.
To keep the current functionality, the option to explicitly enable receive tabs could be on by default and set as a sub-option of “Open tabs” syncing.