Hi, in order for Ghostery to block trackers and ads, it needs to be able to detect and take action on elements of a web page as you browse. We do not record sensitive information(including login credentials as you browse), record browsing history, or disclose user data. Note that despite the prompt being new, Ghostery is not introducing any new permissions with the update. You can read about this in greater detail on our FAQ page, here: https://www.ghostery.com/faqs/why-am-i-being-prompted-to-approve-an-update-from-ghostery/
We are also open source, which you can view here: https://github.com/ghostery/ghostery-extension