I am pretty sure most extensions (or at least ublock) can be set to stay off on specific websites? The extension can have an extra list of known safe sites that don't have ads where the extension stays off by default (should still be turn on-able because the list might be outdated).

In uBlock's case, when you first install it on Firefox you are peomoted to give it permission to "Access data for all websites that you visit". Even if you disable adblocking on a specific website Unlock still has access to it and can see it.

I didn't miss it. That exposure is only a problem if the ad blocker extension misbehaves. It's a theoretical problem.