Good news, the close button is there. On dark themes it renders almost invisible, so it’s hard to notice. A couple ways to click it:
Click the very top-right corner of the banner card, the X is hiding there. Hover your cursor in the corner and it should switch to a pointer. One click closes the banner forever.
If you can’t hit it blindly, temporarily switch to a light theme using Cmd+K, then Cmd+T. The X shows up normally there, close the banner, then switch back to your theme.
The X being basically invisible on dark themes is a known issue we’re tracking. I can’t share an ETA yet, but I’ll reply here if there’s an update.
