flapping noise at high speed

l322 2009 tdv8 vogue

ive been trying to find whatever this sound can be, ive tried some things from my last post but with no succes, this sound started after i removed my side steps, ive put soft like tape between most parts that could be making this sound but without luck, ive got the sound on video

this sound starts at around 120/140km/h
im all out of ideas and getting super frustrated with this
ive hung my head out of the window from the back seet with someone else driving but there is nothing on the outside that is making the noise

It's the JLR "TOO FAST" noise.
It is a well-known fact that JLR (in cahoots with government agencies) have made it impossible to travel at over 70MPH without an annoying noise.
Sometimes the noise is behind the vehicle and goes "Nee-Naw" or "Woo-Woo" and has flashing lights attached to it.

As you surmise, it has to be a windspeed-activated "flapper" somewhere.
Good luck with your search.

Sounds to me like cheap plastic rubbing against more cheap plastic..

Have you checked all you underneath trim. Might only be one fastener missing, enough that it vibrates at higher wind speeds, but looks fine with a visual inspection

Sounds more like a rattle than a flap.
Completely aside from all that: stop using a bloody camera whilst you drive. Did you learn nothing from your previous crash, about how precarious our grip on life is, when in a fast moving metal box. Oh and it's against the law , even in the Netherlands.

What's Dutch Scottish for 'shut your miserable hole'?