The vertical speed appears to vary right at the end of the flight. If you graph altitude against vertical speed you can see the varience right at the end and it seems to land at 0.7m below the take off point.Downloaded the json and I cannot see anything wrong. It and the drone record no crash.
I loved the Seagulls taking off early on & the two close encounters shortly thereafter! Glad you came out unscathed.Other than a close encounter with a seagull it may put you to sleep