F2Pool, the 3rd largest Bitcoin mining pool, might be censoring transactions from an address subject to U.S. Government sanctions.
The Bitcoin development-focused blogger 0xB10C wrote No.20 that his "miningpool-observer" project "detected six missing transactions spending from OFAC-sanctioned addresses." OFAC stands for the Office of Foreign Assets Control, a U.S. Government agency efforts to enforce economic sanctions.
"The transactions missing from F2Pool's block are, however, likely filtered." according to the blogger.
A mining pool is a group of cryptocurrency miners who combine their computational resources over a network to strengthen the probability of finding a block or successfully mining for cryptocurrency. And participants in a mining pool can, relatively easily, switch to a different pool.
F2Pool is responsible for about 14% of mined Bitcoin blocks over the past year, the third-most after Foundry USA's 30% and AntPool's 22%, based on data from Blockchain.com.