Same thing happened to me. I restarted the Steamdeck and verified files and now it works again

I just reinstalled GTA 4 last night and it froze in the same manner… I just restarted the install and it fixed itself.

I had this happen when I bought it the other day, restarting it did nothing. But I noticed when I pressed the steam button that the rockstar launcher was another window open under “GTA IV” so I clicked that and went through the set up and no more issues

Downloaded a few days ago and had to restart the install as well.