Apologies for being unable to exactly state the steps to reproduce, but I've noticed the following on en.wikipedia.org in private browsing with Firefox 110:
- sometimes, clicking the X button any number of times will not dismiss the site notice
- clicking through to the link for "We've made a few changes", going back, and clicking the X sometimes does not dismiss the site notice
- sometimes 2 or more clicks to the X button will close the notice
In the above scenarios, I do not see any JS console errors.
Tagging with Vector 2022 for awareness, since that project has an active site notice, but I can also reproduce this issue with ?useskin=vector. I'm not sure what other project tags to use for site notices.