It's very difficult to see how much the banners are effected, since we don't know the cause. It's only people from the ar community that say "we don't see the banners!".

After the Movement Charter vote in July I asked for some numbers with WMF, also because of the BoT election banner being scheduled in September - as I said: we don't know how much of the banners are effected, and what messages people are and aren't seeing...
The traffic numbers for UCoC/BoT/MC banners were collected here, but never completed so hard to compare. According to @RamzyM-WMF they were normal numbers for the size of the community.

With a search I did found this page: https://ar.wikipedia.org/wiki/MediaWiki:Gadget-HideFundraisingNotice.css
It is not clear how this page has been used.

That HideFundraisingNotice gadget isn't in the definitions list at all, so won't have any effect: https://ar.wikipedia.org/wiki/Special:Gadgets?uselang=en

The only other direct centralnotice reference I found in site CSS is https://ar.wikipedia.org/wiki/MediaWiki:Common.css#L-1039 which hides banners on the Main Page only e.g. https://ar.wikipedia.org/wiki/?banner=wlm_2024_ly. However I can still see banners using preview on other pages

There is https://ar.wikipedia.org/wiki/MediaWiki:Gadget-ArabicAds.js enabled for everyone which is doing something to the sitenotice, perhaps that might have some side effect on centralnotice since it also lives in the sitenotice div?

Having tested the ArabicAds.js gadget and looked at the code a bit more, I don't see anything which would hide centralnotices. I tested closing one of the ads, and also the Anonnotice, and neither hid the centralnotice banner.

I can also see my currently expected centralnotice (wlm_2024_gb) when visiting any page other than the Main Page at ar.wikipedia.org and ar.m.wikipedia.org. Both when logged in and logged out.

So I don't see anything actually hiding the centralnotice across the wiki. However the combination of hiding it on the Main Page, the permanent and prominent Anonnotice, and the sometimes additional "ad" banners (there isn't one running right now, but I put a screenshot with a recent one below) really can't be helping centralnotice campaign performance.

After clearing CentralNotice local storage, the notices are shown. I cleared local storage because I think I closed these notices before.