@Null
So I just watched the stream and God bless you for not being clued up on drugs, but as for the nitrous oxide as an ex drug user of all kinds, I'll give you a better explanation for the nitrous oxide / rekita thing.
Nitrous oxide does have a reaction within the brain, it's called an NMDA inhibitor which is a common anesthesia for mechanism of action. Hence why it's common in dentist practices and ambulances as a quick, safe way to stop pain. Could you imagine the legal ramifications of medical professionals starving a patient of oxygen?
What you are confusing it with is things like propane or inhalants which just take the space of oxygen.
It is classified as a psychoactive drug in most countries.
The reason it causes the octave drop is because while it is still in the lungs it is heavier than air and is basically the opposite of how helium works, if you think about it logically, you could just get high off of helium if it was just about displacing oxygen and children use helium all the time to make their voices higher.
It doesn't show up on drugs tests as the high is so short it is out of your system within minutes, the high itself lasts only for a minute.
Whoever is telling you your info on drugs is just taking stabs in the dark sorry to tell you.
Also Kanye West was always a bit retarded, any prolonged drug use can cause temporary head fuck. Hopefully temporary, but excessive use obviously runs the risk, not just mechanically from the drug but I find it is more so the lifestyle of bumming about and not doing proactive things. While I used I still read, still went to the gym and still socialised with non users, so I dont really feel any less intelligent, but I was around many people whos entire life was drugs, so obviously they declined mentally.
So yeah, it is a classic drug, doesn't cause oxygen starvation (as it usually comes pre mixed with oxygen) and is not detectable because it has such a short half life no standard drug panel test looks for it, and it only has the voice lowering effect while the gas is in your lungs.