I know you’re being facetious, but I’m thinking through the implications of someone actually doing this. ISPs aren’t always handing out static IPv6 prefixes for some damn reason, so you can’t count on that address staying the same when self-hosting. Even if you can, you don’t know what will happen when you change ISPs.
Don’t be ridiculous, I’m going to use an open source password manager to fill an IPv6 address for my email server into the DoorDash signin page.
I know you’re being facetious, but I’m thinking through the implications of someone actually doing this. ISPs aren’t always handing out static IPv6 prefixes for some damn reason, so you can’t count on that address staying the same when self-hosting. Even if you can, you don’t know what will happen when you change ISPs.
So yeah, really bad idea regardless.