There are 893 vulnerabilities listed of severity 9.0 or greater, such as remote code execution and similarly dire problems. Flash may have been innovative, but from a security perspective it's hot garbage and it's long past time to get rid of it.
Flash was a true enabler and was supposed to be replaced by HTML5 which has never fulfilled its intended purpose.
Security was never a problem as that could be dealt with by having access source code and fixing the bugs in it, and that didn't stop Google from continue to ship it years after it got deprecated.
Its even more amazing how Mozilla couldn't succeed or abandoned their effort to create a flashplayer, yet ruffle.rs is creating a Flashplayer in both the Rust language and the web assembly system created by Mozilla.
It apparently never occurred to Mozilla that they could write the Flashplayer in C and compile it in Web Assembly.
Expected behaviour from a company ever so reluctant to bite the hand that feeds it.