As my next door neighbour speaks like this all the time (apart from when she's shouting at her kids).
This woman is nearly 50 and I wish I could record her so you could hear it. It goes up and down and it's like she's trying to imitate her 3yr old daughter.
I just really don't understand why you would speak like this. It cannot be natural.
Thankfully the sound proofing has dampened most of it when we are in the house but as the weather is reasonable today, they will be in the garden all day so I can hear it. 🫣