RequestPollKeyboardButton#requestPoll is required parameter for now

src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/types/buttons/KeyboardButton.kt

@@ -41,7 +41,7 @@ data class RequestLocationKeyboardButton(
 data class RequestPollKeyboardButton(
     override val text: String,
     @SerialName(requestPollField)
-    val requestPoll: KeyboardButtonPollType = RegularKeyboardButtonPollType
+    val requestPoll: KeyboardButtonPollType
 ) : KeyboardButton()
 
 @Serializer(KeyboardButton::class)

src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/types/buttons/KeyboardButtonPollType.kt

@@ -43,9 +43,13 @@ internal object KeyboardButtonPollTypeSerializer : KSerializer<KeyboardButtonPol
      * Crutch due to the fact that direct serialization of objects currently does not work perfectly
      */
     override fun serialize(encoder: Encoder, obj: KeyboardButtonPollType) {
-        UnknownKeyboardButtonPollType.serializer().serialize(
+        JsonObjectSerializer.serialize(
             encoder,
-            (obj as? UnknownKeyboardButtonPollType) ?: UnknownKeyboardButtonPollType(obj.type)
+            JsonObject(
+                mapOf(
+                    typeField to JsonPrimitive(obj.type)
+                )
+            )
         )
     }
 }