The number provided by Google is sufficient if you have only one extension that relies on the declarative NetRequest API in Manifest V3 to block ads. Since at the core of any ad-blocking extension is the filtering rules that teach it to detect ads, such restrictions can become a real snag. As for user-added (“dynamic”) rules, they are capped at mere 5,000. Namely, Chrome has set a guaranteed minimum limit of 30,000 built-in (“static”) rules per extension and a total limit of 330,000 static rules. The problem with Manifest V3 is that it limits the number of built-in and user-added rules for extensions installed by an individual user. Google notes that this will prevent extensions, including ad blockers, from accessing “potentially sensitive user data,” and will make them “safer to everyone.” The downside is, this change will also cause ad blockers to lose some of their functionality. The new, narrower API gives the right to modify requests to the browser itself, while the extension simply announces or “declares” a set of rules by which the browser should respond.

For example, previously the browser would ask a content-blocking extension what to do with a particular web request, and the extension would respond by either greenlighting, blocking or redirecting it.

The API introduces significant changes to the rules that extensions have to follow, such as which browser features an extension has access to and can modify.

Adblock for firefox mobile