As shown in the screenshot.
Oops, this looks like the dotdotdot menu that is rendered wrong. My guess just from the screenshot, is that it is rendered as if it's a subitem of a bundle, without being a bundle, in a weird location.
Can you tell me where you saw this?
On second inspection, this is weird, it looks like this is a read notification, and as far as I remember, CX notifications shouldn't have the dotdotdot visible in a read state at all to begin with.
This is definitely a bug, and I doubt it only happens to CX notifications. It looks like it exposes some more general problem with the rendering/structure of the notifications, but I could use help pinpointing where it happens.
I tried to test it with @Mooeypoo a bit. It doesn't appear in production now, probably because of the deployment train rollback. The three dots is a new feature, which was in production on Friday when the bug was reported, but is not deployed at the moment.
This should be tested again when the the master of Notifications is deployed (or in Beta, but Beta has its own issues :/ ).