I was flying forward in normal mode and suddenly the drone spun and fell into the water. Everything happened so quickly that I did not understand what caused it.
You were flying west at 25+ mph (full right stick) and started to ascend at 428.3 seconds.
At 429.7 sec, it started to slowly rotate counted-clockwise, gradually spinning faster.
At 431.1 sec the Not Enough Force Error messages started showing.
You kept both sticks pushed forward.
At 434 seconds the rotation accelerated and drone tipped hard to the left, going past 90 degrees and started crazy tumbling movements and losing height.
From 435.7, the extreme tumbling recovered a little, with pitch and roll data back between zero and 20 degrees, but the rotation of the drone continued extremely fast as it continued to lose height, now in autolanding mode, but falling at approx 30 ft/sec, much faster than normal descending.
This doesn't look like a normal lost prop incident.
If it was, the drone wouldn't have recovered from the tumbling.
That it was able to partially recover suggests that a prop was significantly damaged, possibly losing one blade.
The not enough force message is because the flight controller pushed one motor to maximum speed but the drone didn't respond as it should.
The loss of GPS was because the drone tipped too far from level and then spun so fast as it came down.
I suspect that if you could recover the wreckage, the damage to one prop would be obvious.