Realm Query to MongoDB

Good evening,

I am trying to run queries against the atlas database from the RealmService.
But when using the FindOneAsync(Object, Object, Object) method and using the parameter to apply query filters, that method does not apply the query filter.

Base Clase

Fragment of Code

  Usuario usuario = new()
                IdUsuario = "user1",
                Correo = "",
                Nombre = "user1"               

            Usuario usuario2 = new()
                IdUsuario = "user2",
                Correo = "",
                Nombre = "user2"

            var dataExterna = Conexion.Instance.MongoCliente.GetDatabase("General").GetCollection<BsonDocument>("Usuario");
            var FilterBson = Builders<BsonDocument>.Filter.Eq("Nombre", "user1");
            var DataExterna = await dataExterna.FindAsync(FilterBson);
            //Return 2 items, is incorrect, the correct is 1 item
            var dataTipada = Conexion.Instance.MongoCliente.GetDatabase("General").GetCollection<Usuario>("Usuario");
            var FilterType = Builders<Usuario>.Filter.Eq(o=>o.Nombre, "user1");
            var DataTipada = await dataExterna.FindAsync(FilterType);
            //Return 2 items, is incorrect, the correct is 1 item

Could you help me indicating what is wrong, or perhaps some parameter that I am not considering.