@gironth ,
Are you able to Disable and delete the ingredients / pieces of your “Sync devices list” . . . and then create a new “Sync devices list” from scratch?
As a precaution, I suggest, that you create backups of your BraveSoftware folder . . . and place those backups on an attached, external drive.
BraveSoftware folder location on Windows OS:
%USERPROFILE%\AppData\Local\BraveSoftware\
BraveSoftware folder location on Linux OS:
$HOME/.config/BraveSoftware/
Re the Trash Can icon - probably the Sync chain has to be unbroken, for that “switch” to work. And that would be a reason, to create a whole new Sync chain with the gear that you still have.
Tip, you might be able to disable a Sync chain via brave://sync-internals
@Chocoholic might have some tips.
Also, see: