HI Jurgster, When you select clear cache, you can uncheck the add on option. How to clear the Firefox cache

Those are desktop options and not mobile. As my title suggest with it being Android.

Ah, if you open Settings, tap on Privacy, then tap on Clear now a list will pop open. (Browsing history, Downloads, Form & Search history, Cookies & active logins, Saved passwords, cache, Offline website data, and Site settings) There are no add ons listed.

If you do not see this list, please make sure that your app is updated from the Google Play app.

What addons are disappearing? I tested with Phony and Last pass.

Firefox for Android settings layout.

And my efforts to clear the cache here in the system settings to my experience removed my add-ons. Basically it flushed Firefox to a sort of factory reset.