Banner dismiss icon isn't marked up as a button

The banners sometimes displayed at the top of the page:


have a close button that isn't marked up as a button, which is an accessibility issue:

image

I can't dismiss the banner with Vimium, and I imagine it also causes problems for users who don't use a traditional mouse due to a disability.

Is this banner part of Discourse, or a plugin? Is there any way it can be made more accessible?

It's a part of Discourse. The "New Week, New Rust" thing is added as a banner pinned topic.

It also seems quite useless, because it doesn't actually link to the topic in question. It should probably just be a regular pin rather than a banner pin.