>>10023547Pomu didn't want to talk about it during the collab - first she said No, and then when asked for details, she said she was just going to be gone for a couple of weeks, and at that point Haruka said it was because she was having a surgery.
As for the surgery, Pomu didn't really want to specify. On one of Pomu's own streams, she said it was a preventative surgery for something that runs in the family, and is something that both her mom and her sister had done to them.
In a separate stream weeks after her return, she mentioned that her grandma got breast cancer twice.
So, if you put two and two together, you might get an idea.