As I recall, one could create accounts on Stack Exchange sites by clicking the login with Stack Exchange button. At present, I encounter the error "Adblock interferes with login, please disable it." message when attempting to do so.
I've reproduced this behavior in Safari after restarting with all extensions disabled. I've no local proxies editing the pages either.
I've no evidence that this Italian ISP interferes with any pages, certainly my default Chrome browser's various blocking extensions block all the usual trackers.