Ruffle is an open-source reimplementation of Flash player. The only differences there are stem from the fact that Ruffle is still very much a work in progress.

Ruffle is an open-source reimplementation of Flash player. The only differences there are stem from the fact that Ruffle is still very much a work in progress. While you can't install a plugin any more, you can still install a standalone Flash player. I even have it on my M1 Mac. Works surprisingly well.