Me too, I've been waiting for something like this for a while.
If I was somewhat younger or if AI wasn't booming, I would try learning Mandarin, but learning a third language is a pain in the ass, especially if you're past your early 20s and the novelty and excitment of communicating with foreign cultures has faded out.
I don't think being older has anything to do. My uncle learnt Swedish at 60, my girlfriend is learning English at 40, and I'd love to learn a 4th language.
What fades after your 20s is the available time - I see a lot of retired people learning languages here.
If I was somewhat younger or if AI wasn't booming, I would try learning Mandarin, but learning a third language is a pain in the ass, especially if you're past your early 20s and the novelty and excitment of communicating with foreign cultures has faded out.