Surprisingly "Easy Chart" not representing correct values for the marked range in 1st screenshot.
The temperature value was above 40°C for more period than it was represented in the chart. Those values are captured in "Database Query Browser" however not displayed in chart.
I have posted few screenshots which would help you to investigate or analyze more why it is happening.
I think you might have a time zone issue with your conversion from milliseconds. The result you are seeing in the SQL query is GMT, however it seems to me that the easy chart is 5 hours out. The temperature appears to spike around 4:23 AM.
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