Some pop-ups are third-party ads that use phishing tactics-like warnings or prizes-to trick you into believing they’re from Apple or another trusted company, so you’ll share personal or financial information. Pop-ups can be ads, notices, offers, or alerts that open in your current browser window, in a new window, or in another tab. But whenever I open a new window, it pops up. I deleted history, uninstalled and reinstalled the flash player. But, whenever I open a new window of firefox, the download prompt 'installflashplayerosx.dmg' keeps popping up.
I downloaded the latest version of Adobe Flash Player for Firefox. I use a MacBook Pro running on MacOS 10.14.2 (Mojave), the Adobe Flash Player asks me to install an update and I do so, the very next day it keeps asking me to again update and does not stop asking until I install again, then even after I install second time it keeps popping up and asking me to update.