You can toggle the type with the logo on the left if you're using Amethyst.
Might be different DM types. Amethyst has a new DM type that is not supported by many other clients.
Discussion
The "new" DM type is superior and is like a year old or something. Everyone else needs to catch up and actually give a crap about privacy. 0xchat supports it as well. It doesn't leak your chat metadata to the world.
That's one of the reasons I use Amethyst as my main nostr client. Quality and features are really really good. Competition between clients and education of users solve that problem.
Please explain for a tech retard. Toggle where? And type?

The little purple guy on the left of "reply here.." is a toggle to change the type of DM you're sending. It defaults to the newer, better, more private kind, but not all clients happen to use it yet.
So if I click it off, then if the other client doesn't use it, it should go thru, but I'll have less privacy?