I am trying to install Adobe Flash player in Firefox 84.0 (the last version support Flash player) when running in a docker container (Ubuntu 22.04.3 LTS). I had tried to run Firefox in my real machine (Linux 6.1.0-17-amd64 Debian 12) and it worked well. I just copy the file "libflashplayer.so" to the path "~/.mozilla/plugins". But when Firefox is running in a container, I do the same but it can't found Flash player plugin. No matter where I place the libflashplayer.so, like "~/.mozilla/plugins" or "/usr/lib/firefox/firefox", it don't work, I can't find Flash player in "about:plugins" or "about:addons". I start Firefox from a terminal and there is no error log. I have no idea why it can detect flash player plugin while running in a real system but don't work when running in a container. Thanks.