Hi! Thanks for your feedback, and sorry for the late reply. Here are some answers in case other users have similar questions:

The buttons to close all tabs or other tabs are limited because the Web Extensions API on Firefox Mobile doesn’t provide access to the full list of open tabs, only the loaded ones. I’d like to find a workaround for this in a future update.

About tabs header like desktop, Firefox developers are working on it! This feature is currently being tested in the Nightly version, though I’m not sure if it’s also in Beta.

About the UI, extensions cannot make changes to the browser UI, and it’s unlikely this will be allowed anytime soon. Some settings are provided to make it as unintrusive as possible, such as moving the toolbar to the top or bottom, hiding it, or adjusting its transparency to ensure users can see important content behind it.

Please feel free to share any other issues or suggestions on the GitHub repo. Have a great day!