The 2 "X" buttons in the flyout, for a cross-wiki bundle, do different things.

• The "X" icons for individual notifications, will "mark as read" (as expected).
• The top "X" icon only removes the bundle from view - because we want to avoid editors accidentally "marking as read" many notifications at once, without an easy way to undo the action or find them again.

Some changes to the icons are planned in T126214: Improve notification read/unread controls and make status indication more clear, but the cross-wiki bundle button needs a distinct decision.

(Some users have reported confusion, as to why clicking the "X" didn't successfully "mark all as read")