Just a couple of big guys switched somewhere else and I doubt it was a bch pool, because for them time lost on mining the useless clone would never be compensated.
As for home miners, some might have gone elsewhere due to somewhat smaller payouts than expected. Last December I was also one of those who were terrified by the downstreak of luck and left kano pool for a month, but not this time. Our fears and "common sense" often disagree with mathematics