20-04 dist-upgrade 后大量软件消失

我在 20.04，拖延更新到 22.04（旧系统，需要先研究性能影响）。

我一直收到“部分升级”消息，并希望它们消失，所以我只是做了一个 apt update + dist-upgrade。

今天早上，我发现很多软件不见了。Gimp、Kdenlive，甚至 ffmpeg！

当我尝试重新安装 ffmpeg 时，我得到：

sudo apt-get install ffmpeg
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 ffmpeg : Depends: libavcodec58 (= 7:4.4.3-0ubuntu1~20.04.sav3)
          Depends: libavdevice58 (= 7:4.4.3-0ubuntu1~20.04.sav3) but it is not going to be installed
          Depends: libavfilter7 (= 7:4.4.3-0ubuntu1~20.04.sav3)
          Depends: libavformat58 (= 7:4.4.3-0ubuntu1~20.04.sav3)
E: Unable to correct problems, you have held broken packages.

是什么赋予了？为什么更新会删除我明显使用的东西？我猜 dist-upgrade 会主动删除仍在使用的依赖项。永远不要再用那个命令哈哈。

我怎样才能解决这个问题？我基本上只需要咬紧牙关，让它升级到 22.04，然后手动重新安装所有让 Thanos-snapped 远离我的软件吗？

预计到达时间：

如果我追踪图书馆的踪迹，我最终会找到：

E: Package 'libilbc3' has no installation candidate