The working way to do this is documented here - https://www.naturalborncoder.com/miscellaneous/2021/06/08/tabs-outliner-backup-and-restore/
The key location you need to know about is shown below, %USERNAME% is your current Windows username. We’ll call this the working directory.
NOTE: The “Default” towards the end is the name of the Chrome profile you are working with. If you have multiple profiles you’ll have multiple paths like this with profile names replacing the “Default”. I don’t use multiple profiles and I can’t remember ever seeing anyone use them so chances are “Default” is all you need to know about.
Within the working directory are two sub-folders called:
These are the folders that contain the current working data for Tabs Outliner and they need to be backed up. I use the free Veeam Backup Community Edition to backup my whole home folder and store it on my NAS, this captures the above folder as part of that process.
You can also expand the whole tree in the Tabs Outliner window and right click Save As on that window. This will give you a web page that contains all the tabs in your tree. This feature really only seems to be useful for emergencies though.
This process is, unfortunately, a bit involved but relatively simple.
Customer support service by UserEcho