Thanks for your review. It's currently possible via a hidden option. Export your settings and change the value of "tabMenuEnabled" in the exported file to false (it's set to true by default). Then, you just have to import this modified file and the menu entry should disappear.

Edit:
You're welcome!

Hi, thanks for the review. This was a Firefox issue, cf. https://blog.mozilla.org/addons/2019/05/04/update-regarding-add-ons-in-firefox/. Unfortunately, there is nothing I can do personally to correct this problem. It should be fixed if you let Android updating your browser.

Edit: I published approximately 10 versions since your review. Are you still unable to install the extension?

Thank you for the review. I do my best to make the saved pages as small as possible by removing the most of unnecessary HTML and CSS. It is already a lot of work, unfortunately I can't do more.

Edit: actually I can do more, check SingleFileZ here: https://github.com/gildas-lormeau/SingleFileZ

Thank you! Now there's also SingleFileZ :)
More info here: https://addons.mozilla.org/firefox/addon/singlefilez