Flash browser plug in has been criticized in the industry for years because of its many security holes and excessive memory demands. Also, it uses so much power that it can’t be used on mobile devices. Adobe’s decision to retire it in 2020 was announced in 2017.
Other games have been migrating away from it. My game Seaport also has a lot of Windows players and they switched their Windows version to WebGL about a year ago. I guess each game maker has to decide which games to migrate and which to discontinue.
Adobe had $2.95 billion in revenue last year, so they aren’t in trouble. It’s just the browser plug-in that’s being dropped.