Original TruncateBytes extension method wasn't working right, seemed to include an extra character which would put us over the limit. Replaced it and new method seems to be working as expected albeit not as nice looking.

KfChatDotNetBot/Extensions.cs

@@ -115,10 +115,18 @@ public static class Extensions
 
     public static string TruncateBytes(this string s, int limitBytes)
     {
-        return Encoding.UTF8.GetString(
-            Encoding.UTF8.GetBytes(s)
-                .Take(limitBytes)
-                .ToArray()
-        ).TrimEnd();
+        if (string.IsNullOrEmpty(s) || limitBytes <= 0)
+        {
+            return string.Empty;
+        }
+
+        if (s.Utf8LengthBytes() <= limitBytes)
+        {
+            return s;
+        }
+
+        var bytes = Encoding.UTF8.GetBytes(s);
+        var charCount = Encoding.UTF8.GetCharCount(bytes, 0, limitBytes);
+        return s.Substring(0, charCount);
     }
 }