Works fine and according to its own description is highly optimized. But the font size is pretty small and not customizable. E.g. Tab Counter Icon is much better in this regard.

Works, but the number is way too small where there are > 1000 tabs, and there is no way to increase it, despite the large amount of empty wasted space around it.

Needs to update text/numbers color on dark mode.

Honestly, this seems to be one of the better tab counter addons on AMO... I've just been through testing about 15 of them, so I should know.

Unlike many addons on the site, the author has a very good description and screenshots and does not skimp on features.

In fact, the only thing this addon doesn't have that I really wish it did is some way to increase the font size (the *only* tab counter addon I found that has a larger font size was 'Tab Count Icon by lllusion3418' but it doesn't have as many options as this one does). I'm viewing from about 10ft away on a 50" TV set to 1920x1080. From there, TCI's font appears ~ 2x larger than TCP's. I can make both out but only just barely on TCP's.

Overall, a very solid addon. I hope increased font sizes become a thing but due to shortage of addons with this feature, I can only assume that it is difficult to do from WebExtensions. If I wasn't holding out for that or I could get me some robot eyes, then I would have no issue calling it the best one on AMO :-)

FF v89.0.2 on Fedora 33 Cinnamon

Thanks for the addon, it's working well so far.

Have you abandoned it now, or will we see some updates soon?

It's good, it doesn't worth the "plus" in the name, as it's simply a tab counter, but it's the only one I've found that allows the customization of the background AND the customization of the font color, and the only one allowing the customization of the message it displays when you hover your mouse on the icon. Allows 2 modes, icon mode and badge mode. It's not the most customizable, but it's a good one.