I was having the same issues folks g have been reporting with running Soul Hackers 2 on the Deck.

But, there was a Steam OS version update in the last couple days. After applying it, I gave Soul Hackers 2 another try from gaming mode.

The result? Soul Hackers 2 is working in gaming mode once again, with no special version selected under properties.

I mentioned this in a response to an earlier post but decided to elevate it so folks will see it.

Give it a try: let's see if we can validate this finding, and then move on...