Back in 2018, my Tarot 650 Sport crashed after many successful flights. Recently, I came across some old video and watched the crash video and spotted the cause:
Glad you found it you was lucky camera was on target , I always heat shrink any bullet connectors after I had one come apart on a large helicopter lucky I know how to do auto rotation
This is the main reason bullet connectors fell out of style. I like to solder everything directly, avoiding any kind of plugs if at all possible for piece of mind.