Toddler speaking made-up language

Hi everyone
My 3,5 y.o has started to speak in her own made-up language - first it’s started when she was playing by herself, but now it’s creeping up into all of her conversations on the daily basis. Now, I remember myself as a child doing similar thing - singing songs in made-up language or talking to myself. I can’t remember me trying to pretend it’s a real language in everyday life and talk to people in it, and I think I was much older that 3,5. I think my excuse was that I wanted to speak some other language, but it was not available to me (I grew up monolingual). But she speaks very advanced (for her age) English and learning 2 other languages, so I don’t think it’s the same issue here. It’s a bit irritating, as she insist on speaking it and also keeps making up all sorts of geographical locations with silly names despite us doing quite a bit of geography with her as well - so she has all this real words from other languages and real geography to practice but she reverts to gibber-gabber, almost a baby language.
Has anyone had the same experience and how to deal with it?

I have about three pages double sided of words and songs that my sons have made up. They’ve been doing it for years and I just assume that it’s something that they’ll eventually grow out of but hopefully they’ll continue to make songs though.