So in my case (I didn't want to, but not my choice, but at least it was cheap and without subscription at the time), it was about the water cooling/warming. It's really nice and essentially inaudible.

I think Chilipad is a brand that does it without the online bullshit, though I didn't get to try that.

None of this should ever require an internet connection, and it's abundantly clear that's an anti-consumer hostile forced behavior Eight Sleep did.