TLDR: I realised that I can’t activate the hotspot if I am in flight mode. As particular as it might seem, I might need to use the phone as a hotspot without connecting to the internet.
The long story: I have a group of guests coming. I kinda found a way to conference call them while going around, without the need to connect to the internet, but I will have to connect the guest devices among them. I don’t want them to use my data in the meanwhile, tho’. I thought I could turn the flight mode on, but I realised that the hotspot stops working, then.
I don’t think the two things need to be connected, and I this is one case where the dis-connection would be useful.