Earlier this year, we reported on a situation regarding Chrome and proposed changes to ad blocking that would greatly limit the ability of modern adblockers to filter content. Under Google’s new rules, extensions would be limited to a list of 30,000 items to be filtered. uBlock Origin, a popular ad blocking utility, currently ships with 90,000 filters, and supports up to half a million. But then, after massive user outcry, Google seemed to reverse course. The company announced that new dynamic lists would also be supported, implying this would be a partial solution to the 30K static list limit.
The discussion about what kind of rules the extension community needs versus what Google wants to enable has been ongoing, and Google has published a major response to a prepared document summarizing the extension communities’ concerns that raises new fears about what the company is planning to do. You can read the company’s full response here, but one particular sentence is causing frustration:
“Chrome is deprecating the blocking capabilities of the webRequest API in Manifest V3, not the entire webRequest API (though blocking will still be available to enterprise deployments).”
As far as the total number of available rules, the numbers are still extremely low. The maximum number of static rules is still 30K, the maximum number of dynamic rules is 5K. Regarding this continuing restriction, Google states:
“We are planning to raise these values but we won’t have updated numbers until we can run performance tests to find a good upper bound that will work across all supported devices.”
Why Are People Upset?
There are two ways to read what Google has written, and it depends on which section of the report you emphasize. If you look at the first statement, it states standard ad blocking will only be allowed for enterprise deployments. If you emphasize the second, it means Google is still evaluating the maximum number of list items for both types, and these values will be raised in the future, potentially obviating all concerns.
But there are some specific reasons why extension developers are leery of this justification. Google has leaned hard on the idea that it’s making these changes to improve Chrome performance, but a major suite of extension benchmarks carried out after Google proposed these changes debunked the idea that ad blocking extensions with large lists were causing performance problems. In February, it seemed as though Google was backing down on these claims after the report was published. But the company is still referring to the need to safeguard performance, with no mention in its April report of the performance testing or which performance scenarios, specifically, it’s seeking to improve.
On the other hand, there’s the fact that Google is an advertising company with an obvious overwhelming interest in ensuring people see as many ads as possible. The developers that have responded in-thread since this message was posted have generally been frustrated with the lack of engagement from the Chromium team or any attempt to discuss the relevant benchmark data. There is at least some feeling that Google has not been engaging transparently and in good faith on this issue.
It is unclear how big of an issue this will become. Google has continued to adjust its original Manifest document and could theoretically set new limits for static and dynamic rule counts that allow most adblockers to function normally. At the same time, however, the company has not made those changes yet, and the topic clearly isn’t as settled as we thought it was in February. There’s still a chance that Google intends to cripple the function of adblockers in Chrome, while offering a pittance of support that won’t allow extensions to perform the same level of blocking they do today unless you’re an enterprise user. Even if extension developers can find new ways to work around these restrictions, they may not be capable of duplicating all functionality.
Users who do not wish to download these ‘improvements’ when Google eventually releases them can stop Chrome from updating by refusing to allow Google Update to run as a service, but this will also lock out security updates. Alternatively, there’s Firefox.
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