DbContext.cs

public override async Task<int> SaveChangesAsync(CancellationToken cancellationToken = new CancellationToken())
{
    var modifiedProducts = base.ChangeTracker.Entries<ProductModel>()
        .Where(x => x.State == EntityState.Modified)
        .Select(entry => new ProductModified {ProductId = entry.Entity.Id})
        .ToArray();

    var result = await base.SaveChangesAsync(cancellationToken);

    await _messageBus.Publish(modifiedProducts);

    return result;
}