After peaking to 228 Th/s now it's down below 189 Th/s. Anyone know why??
"Hashrate" is always really estimated hashrate. Finding blocks is a random process with fairly high variance. Based on the rate of blocks found and the current difficulty, the hashrate of the current network of miners is estimated, and usually averaged over a time period.
TL;DR: There is variance, this is normal fluctuation. There was not a mass exodus of hashpower.