In a dark area it completely obscures your face (https://twitter.com/frankus/status/1499257277894705155), and you have plausible deniability in terms of wearing it specifically for defeating cameras.
Is there any downside to these? Such as distracting cars or blinding other cyclists?
So probably no more distracting to the person with the light than the light is to the person wearing the hoodie.
In any case it’s a similar material as road signs that are a similar size.
Exactly. If anything, for this scenario, it would increase your visibility in a good way!
To distract cars - to draw attention to you - so they don't not see you riding / running / walking on the side of the road and run you over?
When I used to ride a motorcycle, I remember lots of riders used to advise having your full lights on when driving during the day, so you were more noticeable to motorists.
However, I noticed a driver holding up their hand to shield their eyes while I was riding during the day.
Needless to say I didn't do that any longer after that.
You want to be noticed but not cause an accident!
One speculative possible downside: others have answered the human aspect, but in the context of security/privacy OP is being perhaps a little blase with "plausible deniability", or at least it may vary by region? I can see why such a jacket could be useful and why a cyclist or jogger or the like would wear one, same as other visibility enhancing gear. But at the same time I've never ever seen such a thing anywhere in our state. And on camera it apparently looks like a neon sign. Sure, that obscures your face, but at the same time it will instantly draw the attention of any human security watching or potentially of AI if it's been tasked to look for such outliers. If it caught on and a quarter or half or whatever people were wearing such things at night then that wouldn't matter again, but anything that makes one "unique" in a crowd, regardless of what it is, represents signal. If someone is the only one (or one of only a couple) wearing something like that then even without their face they could still be tracked uniquely just by that. And with advances in later generation biometrics like gait analysis wearing such a thing might not only fail to stop individualized identification, but also leak information in terms of "this person is trying to hide their identity" which might correlate to groups in ways hard to predict.
Of course again, that could be taken as an argument to try to make all this sort of thing more of a trend, but there is a first-mover calculation to make maybe depending on what someone is trying to accomplish. If one just wants to help hide others or mess around with camera tracking for the fun of it though that'd be no problem. It's the same kind of dilemma as all sorts of other "blend with the crowd" stuff, like Tor say. If everyone ran an onion router (ignoring current gen scaling issues) then there'd be zero signal from doing so, the protection offered would be strongest, and also the vast majority of traffic would be completely boring and legitimate because so would almost all the users. It'd be much harder to crack down on as well. If only a few people run it and specifically do so to conduct covert activity, well the mere act of doing so then potentially leaks a bit. And both sides are subject to reinforcing effects, if "everyone does it" and "it's normal" and "almost entirely legit" then that makes it easy for anyone new to join, constantly reinforcing the network. Conversely if it's something strange with whiffs of criminality, then many won't which in turn reinforces it being strange and those using it maybe having something suspicious going on. Bootstrapping that can be a tough nut.
Anyway just sort of thinking out loud so to speak. For cameras I'm leaning towards ultimately some sort of legal response being needed, and that individuals trying to evade it is probably a losing battle.
Catching criminals is a rarely a sufficient excuse for degradation of privacy for everyone.
10/10, would recommend to pedestrians walking on the steet at night!
10/10, would recommend for very clean hands.