I opened a BRAND NEW Apple leather Magsafe and tried it out. The new one worked better than the old one, but not 100% correctly.
When pulling the new one on and off the iPhone I get the tactile vibration but no immediate visual notification that it was removed. The new one eventually gets some kind of notification after some minutes, but not the proper notification more like a banner one.
So, I'd say that the issue might be a combination of hardware in the Magsafe leather wallet and software issue with 18.0 and 18.0.1
I have not yet tried the 18.1 I will just wait for the official update.
When I phoned Apple they wanted me to delete (not just turn off but delete) any VPN apps I have on the phone, and reset Network settings. From prior experience with this sort of thing, I don't think VPN has anything to do with all this, because all of my AirTags still work fine, so why would MagSafe wallet be any different. Plus the fact that all this started with 18.0 update cannot be simply a coincidence.
Is this UNIVERSAL with EVERYONE who has updated to 18.0 ? I am thinking yes, but that some may be experiencing it just the way I described with the brand new Magsafe wallet, that is, still getting tactile notifications and delayed banner - such that they don't really notice that something is amiss, or think that this is the "new way" MagSafe leather wallet is notified in ios 18 - tactually, delayed or banner only.