I'm hazy on the details, but:

Home Assistant has a well-known public name that opens your local instance. On first access, you need to give it the name or ip of your instance, which is saved in browser storage. This supports deep links into your config from forum posts.

My mum also had a shitty D-Link wifi mesh device, which was packaged as an appliance. I cannot speak lowly enough about that garbage device, but then, I am not really the target market. iirc it had something similar; a public dns name for local appliance mgmt.

How is that the same thing? That is a DNS entry that resolves to an internal IP. That lets a user explicitly type a domain and get something internal. That wouldn’t allow cnn.com to ports scan my fridge.

I remember Fritzbox devices doing the same. Wasn’t a real problem until someone actually hijacked the fritz.box domain.