I don't understand why people think it's some nefarious dark pattern. It's perfectly clear, the old 1Password app is winding down, the future is their hosted version.

The only way to even download the app is if you already knew about it's existence before. It's not a dark pattern, it's just directing people who sign up for 1Password today into their actually supported product instead of the end-of-lifed one. Your app will continue to work for some reasonable amount of time until some version of macOS breaks it, then you can either pick another one from numerous competitors or go with their hosted version. Sounds to me like you'll need look into the alternatives given your requirements. It is what it is, no need to attribute it to malice.