Bitmain Antminer B7, 96 KH/s ASIC, they currently sell it only on their Chinese website... after probably "testing" the new devices for a while in their farms.
Yeah, they are "testing" their hardwares to get as much profit as possible and when they mine enough for them, then announce that they are releasing these asic miners, already tested (in reality very used). It is their politics and everyone knows it well.
But OP, as I see, according to
https://miningpoolstats.stream/bytom <-- F2pool has over 50% hashrate, not Bitmain. Currently Bitmain (antpool) shares 23.3 % of Bytom network hashrate.