I don’t have much experience with noStrudel, but I wonder if they handle DMs differently?

I think there are competing DM NIPs (none of which have great privacy), they may handle DMs completely outside of Nostr, or use dedicated relays for DMs, etc.

DMs are still a bit of a mess, afaik. 

 DMs are just for establishing a communication channel outside of nostr 😂  

 I would not want to send my phone number to someone on here, to start a Signal chat 🤔 

 You can use a username now with signal, but I hear you.