tell us your color management, bits per channel, and output codec settings.
weird. looks like a wrap around of RGB information so bright it went back to 0.
try changing project settings to 16bpc from 8bpc and rendering out a single uncompressed frame like png.
If that doesn’t work, do a quick filter check by adding the effect -Levels and make input 18-235 and output 18-235. 18 being black and 235 being white. Then render out a single frame png again.