Running an older version of a Desktop Environment

I know Deepin is not supported in Manjaro anymore but I think this applies to all Desktop Environments.

Currently Deepin is in development and has issues, so I would like to still use the old version that I have, but also update all my other apps.

I tried updating everything except the deepin packages and my deepin broke, only part of it was working (it was weird).

Similarly, after reverting to an image (I made one, since I had a feeling it might not work) I updated KDE (synced: pacman -S plasma) and now it crashes and sends me right back to the login screen whenever I try to login with plasma.

Moreover, it seems like this is the case with many applications. I tried downgrading or upgrading them with downgrade (I did override ALA with DOWNGRADE_FROM_ALA=1) and they won’t run until I put back the same one.

  1. I was wondering why this is the case?
  2. How can I run an older version of the a Desktop Environment?
  3. And if this isn’t possible, at least how can I make plasma run on my older version of manjaro again as now it’ll just install the new version of plasma that crashes? (However, this is the last resort because I would definitely prefer to update.)