❔ EF core querying issue

namespace DroppsDev.iFoodTracker.Application.Models;

public class Product
{
    /// <summary>
    /// Unique identifier for the Product.
    /// </summary>
    public Guid Id { get; set; }
    
    /// <summary>
    /// Name of the Product.
    /// </summary>
    public string Name { get; set; } = string.Empty;
    
    /// <summary>
    /// Description of the Product.
    /// </summary>
    public string? Description { get; set; }
    
    /// <summary>
    /// Price of the Product.
    /// </summary>
    public decimal Price { get; set; }
    
    /// <summary>
    /// Average rating of the Product.
    /// </summary>
    public float? Rating { get; set; }
    
    /// <summary>
    /// Rating of the Product by the user.
    /// </summary>
    public int? UserRating { get; set; }

    /// <summary>
    /// Navigation property for the ProductRating.
    /// </summary>
    public IEnumerable<ProductRating> ProductRatings { get; set; }
}

namespace DroppsDev.iFoodTracker.Application.Models;

public class ProductRating
{
    /// <summary>
    /// Unique identifier for the Product.
    /// </summary>
    public required Guid ProductId { get; init; }
    
    /// <summary>
    /// Unique identifier for the user.
    /// </summary>
    public required Guid UserId { get; init; }
    
    /// <summary>
    /// Rating of the Product by the user. 1-5.
    /// </summary>
    public required int Rating { get; init; }
    
    /// <summary>
    /// Comment on the Product by the user.
    /// </summary>
    public required string? Comment { get; init; }
    
    /// <summary>
    /// Navigation property for the Product.
    /// </summary>
    public Product Product { get; set; }
}

protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Product>()
            .HasKey(f => f.Id);
        
        modelBuilder.Entity<Product>()
            .Property(f => f.Name)
            .IsRequired();
        
        modelBuilder.Entity<Product>()
            .Property(f => f.Price)
            .HasPrecision(18,2)
            .IsRequired();

        modelBuilder.Entity<Product>()
            .Property(f => f.Description)
            .IsRequired(false);
        
        modelBuilder.Entity<ProductRating>()
            .HasKey(fr => new
            {
                Id = fr.ProductId, fr.UserId
            });

        modelBuilder.Entity<ProductRating>()
            .Property(fr => fr.Rating)
            .IsRequired();
        
        modelBuilder.Entity<ProductRating>()
            .Property(fr => fr.Comment)
            .IsRequired(false);

        modelBuilder.Entity<Product>()
            .HasMany(p => p.ProductRatings)
            .WithOne(p => p.Product)
            .HasForeignKey(p => p.ProductId);
    }

        public async Task<Product?> GetByIdAsync(Guid id, Guid? userId = null, CancellationToken token = default)
        {
            if (userId == null)
            {
                return await _dbContext.Products.FindAsync(new object?[] { id }, cancellationToken: token);
            }

            return await _dbContext.Products
                .Include(f => f.ProductRatings)
                .FirstOrDefaultAsync(f => f.Id == id, cancellationToken: token);
        }