I checked the official Twitch documentation. Twitch added a number of new message tags to look out for. It appears that msg-param-months is only sent on subgift and anonsubgift. Whereas the newer tag msg-param-cumulative-months is sent on sub and resub. Knowing this, you can edit your script accordingly to react using this information. You can always look at all the available message tags there as well and easily come up with creative ways for your bot to reply to any type of subscription (as well as raids and new chatter). I hope this helps.