Adobe will end support for Flash Player at the end of 2020 and encourages content creators to migrate any existing Flash content to new open formats, such as HTML5, WebGL, and WebAssembly.
Check out Adobe's detailed announcement: Flash and the Future of Interactive Content.
Flash Player end-of-life (EOL) impacts playback and authoring of rich media having Flash content (*.flv and *.swf) in PDFs:
Adobe recommends moving away from using Flash content (*.flv and *.swf) in all multimedia workflows in PDFs.
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