Games wont launch with --unshare-network about com.valvesoftware.steam HOT 1 OPEN

Update 1:
Alright, ive tried 2 more now:

Deponia The Complete journey
Spec Ops The Line

Both of which apparently had a linux native version which got installed OOTB, and which opens and runs fine, even when steam is launched with --unshare=network.

The problem seems to occur only when i specifically download the windows versions of these games (by enabling the proton compatibility in the settings)...I pretty much get the same error as the ones mentioned in the logs...that being:

[S_API FAIL] SteamAPI_Init() failed; create pipe failed.pid 2410 != 2409, skipping destruction (fork without exec?)

If this is getting too boring to read
All i wanna know is, how is steam launched normally (but with internet switched off through NetworkManager) able to run these games fine, but when launched with --unshare=network (which I would think does the same thing but just for this flatpak app) , gives these SteamAPI_Init errors all the time (well except for DRM free games) ?

from com.valvesoftware.steam.