What kind of feature are you missing? Where do you notice a shortcoming of PTB?

When replying to messages from a group that has topics enabled using reply methods such as Message.reply_html, the reply is sent to the General topic by default. This is because the Message.reply_html method does not preserve the original message_thread_id.

Upon closer inspection, I see that this is tied to the do_quote parameter - if this parameter is set to True or None then the message is sent to the correct topic and the original message is quoted. If this parameter is set to False then the message is sent to the General topic and the original message is not quoted. There are legitimate use cases where you don't want to quote the original message (e.g. for brevity) but still want the reply to end up in the same thread.

I am using version 20.8 of the library.

Describe the solution you'd like

In my opinion, the intuitive solution is for the reply to go to the same message_thread_id that the message came from by default. This is consistent with the behavior of replying to the same chat_id by default. Of course, if the caller wants to pass a different message_thread_id, that possibility is still available.

Describe alternatives you've considered

One can update their code base to pass the message_thread_id parameter manually to the reply methods, but this seems overkill.

Additional context

I can implement this myself and send a PR, but I was wondering if there was a specific design intent behind this decision.