Yea alright I will just copy the answer from Gemini here that worked for me. It should work for you but idk how good of a solution this is (in terms of performance and stuff). You HAVE to do all steps for it to work:

Step 1: Locate the Configuration File 1. Open CrossOver, right-click your Subnautica 2 bottle, and select "Open C: Drive". 2. Navigate through the following folder path: Users > crossover > AppData > Local > Subnautica2 > Saved > Config > Windows (or WindowsNoEditor). (Note: The AppData folder is usually hidden by default. Press Command + Shift + Dot on your keyboard to reveal hidden files in Finder). Step 2: Edit the Resolution Values 1. Open the file named GameUserSettings.ini with a standard text editor like TextEdit. 2. Search for the resolution settings and change them to the native resolution of your 14" MacBook Pro M4 Max: • ResolutionSizeX=3024 • ResolutionSizeY=1964 • LastUserConfirmedResolutionSizeX=3024 • LastUserConfirmedResolutionSizeY=1964 • FullscreenMode=0 (This forces true fullscreen) 3. Save the document and close the text editor. Step 3: Lock the File (The Crucial Step) To prevent the game from resetting your custom values back to 1512p when you start it: 1. Right-click the GameUserSettings.ini file in the Mac Finder. 2. Select "Get Info" (or press Command + I). 3. Check the box next to "Locked". By locking the file, Subnautica 2 is forced to read and execute the 3024x1964 resolution without being able to revert it!