Computed column in EF Core incorrect mapping

Trying to use a Computed column in my query but it seems EF Core handles it like any other column and just ignores the mapping. Is there somehting i do wrong here? or do i misunderstand the usage of the computed column :S This is almost the same examples as the documentation are using.

EF Core documentation

I am running MapUsers(modelBuilder.Entity<User>()); inside the OnModelCreating.

Mapping:

private static void MapUsers(EntityTypeBuilder<User> entity)
{
    entity.Property(p => p.FullName)
          .HasComputedColumnSql("[FirstName] + ' ' + [LastName]");
    entity.ToTable("User");
}

this is the generated query:

 SELECT [FirstName], [u].[FullName], [u].[LastName]
 FROM [User] AS [u]

Managed to get it to work in the query by using this line instead of using a strongly typed property

$"{u.FirstName} {u.LastName}".Contains(query)