Thank you for helping.
I launched the game on steam os not a win os on steam deck.
I've already looked though my cloud save files of that steam account, and found there's no histories of save files of DAI. Therefore One thing I am positive is our data only goes to EA app cloud.
I had a notification from EA app at later tries, saying my online save file is corrupted. I am not sure how that happened since I didn't even play game since I frustratedly found out local save is lost.
Is there a way to retrieve my save files from your server? from what I see that is the only way to do it now. I'll provide whatever info. that's required.
About the two locations from the thread you shared.
In the first "One for proton in
~\.local\share\Steam\steamapps\compatdata\1637320\pfx\drive_c\users\steamuser\AppData\Roaming\Godot\app_userdata\Dome Keeper"
I digged the path to roaming, found 2 folders there, a “Microsoft” and a "Wine_gecko". And I assumed I should look into the gecko folder. here is what I found, in the attachment.
To be frank I don't know what to look for, what's the format or name of the same file.
and the second path I found nothing at "~\.local\share\godot\app_userdata\Dome Keeper\"
Am I supposed to look for a corporate name, or game name in the app_userdata file? I've found none about bioware, electronic arts or da.inquisition.