well, it's generated column

modules/RichSiteSummary/Data/Post.cs

@@ -5,6 +5,7 @@
 
 using System;
 using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
 using System.Text;
 using Kruzya.TelegramBot.RichSiteSummary.UrchinTrackingModule;
 using Telegram.Bot.Types.Enums;
@@ -84,10 +85,10 @@ public class Post : RepresentableEntity
     public DateTime ReceivedAt { get; set; }
 
     /// <summary>
-    /// 
+    /// SHA256
     /// </summary>
-    [Required]
     [MaxLength(64)]
+    [DatabaseGenerated(DatabaseGeneratedOption.Computed)]
     public string UrlHash { get; set; }
 
     public Post()