This might be one of the stranger VE issues...
In Israel there is an ISP for people who want to voluntarily filter their web experience from unwanted content. Apparently, it can entirely remove links to sites that are legitimate on Wikipedia, but don't pass its test, for example web.archive.org. The user doesn't even notice that it happens, and when the page is saved, the link is removed, and it looks like vandalism, even though it's unintentional.
Here is an example edit - notice a removed external link towards the end of the diff.
It would be nice to prevent it somehow.