Bitcoin is known for its anti-censorship nature and immunity against unwarranted regulations. Yet, a new study reveals that F2Pool, a leading Bitcoin mining pool, has been selectively filtering transactions in line with sanctions set by the US Office of Foreign Assets Control (OFAC). This is a stark contradiction to Bitcoin’s ethos that anyone can make transactions provided they can pay the network fees. The disclosure was made by an anonymous Bitcoin developer, 0xB10C, who discovered six transactions from addresses under OFAC restrictions that were excluded from the blocks. Notably, F2Pool, an Asian Bitcoin mining pool, has become the first to engage in transaction filtering based on US sanctions. Given F2Pool’s status as the third largest Bitcoin mining pool, contributing to 13.7% of all blocks mined in the last year, this could lead to one in seven BTC blocks being mined under a censorship condition if F2Pool continues to filter sanctioned transactions. In response to this development, F2Pool co-founder Chun Wang stated that the Bitcoin mining pool will disable the ‘transaction filtering patch’ until a broader consensus is achieved, confirming F2Pool’s deliberate censorship of transactions sanctioned by OFAC and raising concerns about the potential of such incidents in the future.