Optimize out null checks when translating Enum flags

[BenjaminAbt]

I have an enum with corresponding flags.
The goal now is to check whether a property has one of the passed flags.

    [Flags]
    public enum MyEnumWithFlags
    {
        None = -1,
        RoleA = 1,
        RoleB = 2,
        RoleC = 4,
        RoleD = 8,
        RoleE = 16
    }

    public class MyEntity
    {
          public int Id {get;set;}
          public MyEnumWithFlags MyPropertyWithFlags {get;set;}
     }

Steps to reproduce

 MyEnumWithFlags existingFlags = MyEnumWithFlags.RoleA | MyEnumWithFlags.RoleC;
 var query = await _dbContext.Entities.Where(e => (e.MyPropertyWithFlags & existingFlags) != 0)

Following SQL will be fired:

SELECT [f].[Id], [f].[MyEnumWithFlags] FROM [Entities] AS [f]
WHERE (([f].[MyEnumWithFlags] & @__existingFlags _0) <> 0) OR [f].[MyEnumWithFlags] & @__existingFlags _0 IS NULL)
      ORDER BY [f].[Id]

I don't think this is the correct query: the IS NULL check is unnecessary (column is "int, not null").
If the column could be null, this would even create a wrong query.

Further technical details

EF Core version: 3.0.0
Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: 3.1.0-preview1.19506.1
Operating system: Windows 10
IDE: Visual Studio 2019 16.4 Preview 2