Firefox browsers for Mac and Windows have recently become targets of some malicious website attacks, which display false warning notifications and completely lock up the browser. Hackers use a bug in Firefox to tamper with the browser to achieve their goals without user interaction. Mozilla has not announced a solution, but the problem has caused serious damage and caused problems for users.
The only way to close the window is to force-close the entire browser using either the Windows task manager or the Force Close function in macOS. To resolve the problem, users must force-close Firefox and then, immediately upon restarting it, quickly close the tab of the scammer site before it has time to load.
Mozilla said that Mozilla is currently investigating and making fixes, but there is currently no accurate release time.