I’m not sure entirely sure if it was the latest system update for the Steam Deck, or the newest update for Midnight Suns — which includes the Morbius DLC — but while installing the latest game update I ran into a troublesome error. The game ended up in a loop, downloading the latest update files, and then when it would progress to installation, it would stop completely. I rebooted the Deck, and restarted Steam several times but nothing helped. To make matters worse, every time I paused the download the estimated completion times would jump to days, weeks, and months. It was pretty wild.
To fix the problem I had to restart the Deck entirely. Then, I had to make sure the Midnight Suns download was not in progress. If you’re having this problem with another game the goal is to stop any and all downloads. Then I simply uninstalled the game. You can do this by pressing Start/Options > Uninstall. Then I just reinstalled the game and let it download.
The solution is not ideal and if you have an unreliable or slow internet connection it’s going to take a while but it’s what ultimately worked for me. Hopefully, you don’t run into this error, but if you do now you know a solution to get back into your game(s).