See https://openwrt.org/releases/25.12/notes-25.12.0 and https://openwrt.org/docs/guide-user/installation/attended.sy...

They have the tools and infrastructure for assembling custom firmware images on-demand, and have recently added it to the default images, so they must feel like their infrastructure is ready for significantly increased demand.

I use attended sys upgrade. I've been using OpenWrt for the last 7 years, but I've noticed that attended sys upgrade often fails at release time. And there are often point releases shortly after. I'm just skeptical that their infrastructure would handle mass auto updates at release time. I usually wait a few weeks after release until the masses have reported various device specific bugs before I upgrade.