Rated 5 out of 5 stars

Worked on Thunderbird 110. Sadly on 111.0 it has stopped working. Considering the other crap Mozilla have added to the page, it's almost a minor problem.

I cannot find any setting in Thunderbird 111 to hide the folders. If there is something in about:config it's not obvious.

This review is for a previous version of the add-on (2.1.0). 

Please note:
1.) 110 and 111 are TB beta versions.
2.) As far as I know, 111 has an built-in function to hide the local folders, so the Add-on makes no sense for TB 111 and later versions.

Regarding the setting, here is a hint:
On the right [of the new Folder Pane Header], an accessible “meatball” menu button will allow users to:
...
Show or hide local folders and tags
(Found here:
https://blog.thunderbird.net/2023/02/thunderbird-115-supernova-preview-the-new-folder-pane/)

Addendum on 03.03.2023:
Obviously this function is not yet implemented in TB111, see
https://thunderbird.topicbox.com/groups/beta/Ta2efb9053e846a0c/hide-local-folders

Update 16.06.2023:
The built-in function to hide the local folders has arrived in TB 115.0b3 !!!