timeGroup function group data on Thursday

Environment :

  • Grafana version: latest version 7.0.1
  • Data source type & version: mysql
  • OS Grafana is installed on: centOS
  • User OS & Browser:
  • Grafana plugins:
  • Others:

Hi,

i have a question regarding this timeGroup function, when i use

$__timeGroup(updatetime,‘7d’, 0) as time,

The data is grouped weekly but start from Thursday, can it be from Monday as most of users expect ?
Also from the Query Inspector, it seems the time is deviated by 7 hours
I would expect something like
2020-06-22 00:00:00
2020-06-29 00:00:00

can anyone look into this issue?