How likely is it that those "protestors" are US and Israel propped and the plan is to do another regime change via this route?
Isn't this "son of the late Shah" a guy from the US?
Very, but at the same time the Iranian leadership have been a really shitty government and ran the country into the gutter. People have genuine grievances.
The only way to believe this is if you're a Westerner being fed a purely US-centric media diet. Otherwise you'd know all the ways that the Iranian government has been failing their people recently and for a long time now, and how unhappy Iranians are with their government. You people act like people can't be upset at how they're being treated by their own government without being incited by an external actor. That's honestly quite the dehumanising and insulting way of looking at it.
Also, if the US wanted to do a regime change, they'd just move in militarily a la Venezuela and Trump would be talking about it non-stop. He's not the subtle type, I promise. We'd already know if they were involved.
It is 100% that.
> How likely is it that those "protestors" are US and Israel propped
It's almost sure that both US and Israel are meddling with the current situation. That doesn't mean the situation isn't also started by and wanted by the population.
For a comparison point in the past, the civil rights and antiwar movements in the US were grass-roots movements started by local people with legitimate claims. At the same time, opponents of the US like USSR were involved in stirring these movements, because of course they would.
There isn't much you can infer about the legitimacy of a movement by learning that the movement is helped by foreign intelligence agencies.
The best way you can avoid this kind of confusion is 1) make a society in which malicious actors don't have many latent issues to stir, and 2) make it so your country's intelligence agencies aren't malicious actors. There isn't much else to do.