zlacker

Unlikely. My guess is that the ad code runs in the context of the browser itself or some newly created context, rather than of the page you were reading before, but whatever fetch() or similar call it makes to load the ad goes through a subsystem that is affected by ad blockers.

Put another way, when you allow ublock or whatever you're using permission to intercept requests for ALL pages, that includes the "page" that mozilla is using to serve this ad.

Further evidence in favour of this hypothesis is that the ad can temporarily disable the rest of the firefox UI until you deal with it, which normal pages certainly can't do.