Firefox 69 Will Disable Adobe Flash Plugin by Default (zdnet.com)
Mozilla will take the next major step in disabling support for the Adobe Flash plugin later this year when it releases Firefox 69. From a report: Firefox 69 will be Mozilla's third last step to completely dropping support for the historically buggy plugin, which will reach end of life on December 31, 2020. Flash is the last remaining NPAPI plugin that Firefox supports. Mozilla flagged the change, spotted by Ghacks, in a new bug report that notes "we'll disable Flash by default in Nightly 69 and let that roll out". Firefox 69 stable will be released in early September, according to Mozilla's release calendar.
Use oldversion.com, put an alternate browser install to run along next to your main one.
It's actually not bad for making vector-based animations with interactive components. I believe that was its intended purpose. The issues came when people started using it to design entire web sites.