

This is referring to sharing individual chats via the ChatGPT UI which makes them public and at least used to make them findable via search engines.
Yes, OpenAI still stores everything you type into their text inputs, but no, it’s not visible to the general public by default.
iOS 15 (2021) introduced support for actual extensions, not just blocklists. These extensions can inject scripts on the pages you browse and multiple adblockers on iOS make use of that, including Adguard, uBO Lite and Wipr for example.
They still use the blocklist API for their regular URL blocklists, but can run scripts in addition to that. Never saw a YouTube ad on iOS ever since, for example.
There are even userscripts extensions (think Greasemonkey compatible) available. It’s no problem.