UPDATE

app.py

@@ -110,7 +110,7 @@ async def send_handler(event):
         # output_file = await Fusion.saveSound(states[user_id]["audio"], output_file_name)
         # await event.reply(file=output_file)
 
-        await client.send_file(event.chat_id, file=states[user_id]["audio"], attributes=types.DocumentAttributeFilename(file_name="Audio.mp3"))
+        await client.send_file(event.chat_id, file=states[user_id]["audio"], attributes=[types.DocumentAttributeFilename(file_name="Audio.mp3")])
 
         # Clean up - remove the user's state and the saved audio file
         del states[user_id]