According to Blocky's test logs, restricted access initially began no earlier than Maand no later than March 19, 2022. Firefox in China has a long history of arbitrarily blocking websites even for non-political or legal reasons and was actually found guilty by the Court in China back in 2018 for several such cases. This action of blocking was solely performed by Firefox in China, because the website '' is accessible in China and it's not blocked by China's 'great firewall'. Worth to note: This has nothing to do with China's 'great firewall'.

The facts can be validated by reproducing the test results below.

When users in mainland China try to access the above ad-filtering add-ons on, the website returns 451 Unavailable For Legal Reasons instead of the normal 200 OK response, and the body of the page states 'This page is not available in your region'. Recently, some users reported that uBlock Origin, AdGuard AdBlocker, AdBlock For Firefox, and AdNauseam were restricted from being accessed by users in mainland China. Firefox starts blocking uBlock Origin and other ad-blocking add-ons in China on

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