My dedicated server build keeps deleting my steam_appid

Replacing MyProject and <your_appid> with the appropriate values, something like:

public class MyProjectServerTarget : TargetRules
{
	public MyProjectServerTarget(TargetInfo Target) : base(Target)
	{
		Type = TargetType.Server;
		DefaultBuildSettings = BuildSettingsVersion.V4;
        IncludeOrderVersion = EngineIncludeOrderVersion.Unreal5_3;
        ExtraModuleNames.Add("MyProject");

        GlobalDefinitions.Add("UE_PROJECT_STEAMPRODUCTNAME=\"<your_appid>\"");

        GlobalDefinitions.Add("UE_PROJECT_STEAMGAMEDIR=\"MyProject\"");

        GlobalDefinitions.Add("UE_PROJECT_STEAMGAMEDESC=\"My Project\"");

        GlobalDefinitions.Add("UE_PROJECT_STEAMSHIPPINGID=\"<your_appid>\"");
    }
}