Do they guarantee the hashrate you pay for?  Seems to fluctuate a lot.

{
 "hashrate1m": "4.59P",
 "hashrate5m": "4.63P",
 "hashrate1hr": "6.48P",
 "hashrate1d": "755T",
 "hashrate7d": "113T",
 "lastshare": 1610124259,
 "workers": 15,
 "shares": 16051000000,
 "bestshare": 80356373899.33391,
 "bestever": 80356373899,
 "worker": [
  {
   "workername": "36hJi3UPXt1xCG6SEwUcpn9tcoxYMYkD87",
   "hashrate1m": "4.59P",
   "hashrate5m": "4.63P",
   "hashrate1hr": "6.48P",
   "hashrate1d": "755T",
   "hashrate7d": "113T",
   "lastshare": 1610124259,
   "shares": 16051000000,
   "bestshare": 80356373899.33391,
   "bestever": 80356373899
  }
 ]
}