Hi

What add-ons do you have installed in Firefox for Android? One of them may be blocking scripts from running on web pages you are trying to view.

Oracle has never made a Java Plugin for the Android OS or iOS, only for desktop OS's like Windows, macOS, Linux and for old Solaris versions.

Perhaps you are referring to JavaScript which has no relation to Java as JavaScript was originally going to be called LiveScript. https://kb.mozillazine.org/JavaScript_is_not_Java

There are a few Extensions for Firefox on Android that can change JavaScript settings like NoScript Security Suite and uBlock Origin.