Considering what's happening with tech today, I think #nostr clients, that have E2EE DMs, should have a quick popup note (with a 'don't show this to me again' checkbox) informing users that:

"While Direct Messages are encrypted, be aware that your mobile or PC manufacturer may already be spying on your screen by taking screenshots, recording your screen, and/or logging your keyboard presses, capturing what you're about to send before it gets encrypted. This renders encrypted messaging meaningless unless you take appropriate measures to ensure you are not being monitored."

I'll have that on my client (hopefully I remember) when the DM system gets implemented (hopefully I remember to do that x3).