On January 26, 2021, Mozilla Firefox will end support for Adobe Flash, as announced back in 2017. Adobe and other browsers will also end support for Flash in January. And we are working together to ensure a smooth transition for all.
Firefox version 84 will be the final version to support Flash. On January 26, 2021 when we release Firefox version 85. It will ship without Flash support, improving our performance and security. For our users on Nightly and Beta release channels, Flash support will end on November 17, 2020 and December 14, 2020 respectively. There will be no setting to re-enable Flash support.
The Adobe Flash plugin will stop loading Flash content after January 12, 2021.
See Adobe’s Flash Player End of Life information page for more details.
Source: Mozilla