v.1.1.54337please-note-when-upgrading
Inconsistent ClickHouse Versions May Cause Incorrect Query Results
If different versions of ClickHouse are running on the cluster servers, it is possible that distributed queries using the following functions will have incorrect results:varSamp,varPop,stddevSamp,stddevPop,covarSamp,covarPop,corr. You should update all cluster nodes.