To the people complaining about shrinked search results or that unmatched tabs not hide... you should take a look at the setting where you can change exactly those behavior. Even a look at the Screenshots would have lead you to that conclusion.
You decided to give a bad review instead...

unusable

Not working - no search.

A life saver in tabbed Internet. I have been waiting for a search feature in Tree Style Tabs since years, until I found out that TST offers nice extensions and has a capable API.

Currently doesn't support using the extension's toolbar button while having the browser's toolbar, where the extension's button is, at the bottom of the browser. Extension's window opens below the button, putting the window out of view. Not really a huge deal as it is integrated into TST, so it is still useable.

Working great for me. This also works across containers which not even the native FF tab search does.

It does what it says, and it does it well

Whenever I try to search for a tab by one of the words in its title, it doesn't show or highlight the tab. Its acting like it doesn't exist when I know it does. I don't know if I'm doing something wrong or if I need to un-install and then re-install.

Either nothing happens or I get an error message. Have reinstalled, closed and reopened FF to no avail.

Excellent! Really helps me organize my ridiculous collection of tabs.

Good!
Add dark theme accounting to the settings page. Now I have to write the userCintent style myself.
And the possibility of translation is desirable.

Strange resource heavy implementation. I wish it would just hide unmatched tabs, maybe drawing horiz. lines between results from diff. trees.

Love the addon. It would be cool to have a setting that searches based on tab content but that would probably be pretty extra.

Not many reactions to messages, but the extension works. Great job.