Edit 2026-01: yay, both are fixed!!
- Deleting messages for all participants (e.g. see Retract/edit sent messages and [UX/UI] "Delete Message" doesn't seem to be working as per the expectations the UI sets · Issue #4435 · deltachat/deltachat-desktop · GitHub).
- Calls don’t make the usual ringing sound, see FAQ - Delta Chat :
Note that there is no ring tone on the other side, and your chat partners will not get interrupted by a video chat invite.