I did a 100 km ride with many hills. When it was done I discovered I had set a new 40 km time record.
Is there any way to find out what section of the ride this fastest 40 km time occurred at?
It might be possible to see it in the FIT file if it is written as an event. You will need a software like https://www.fitfilerepairtool.info (FFRT) to view it.
I think you can view the file without a license so try that.
Another alternative is that you share the FIT file with us and someone with FFRT can look at the file.