On the other hand they have zero chance of getting Maduro back by force or of getting any relief by force. They are entirely outgunned and outmatched and have no interest in fighting a long war against the US to emerge victor of the ashes. So sucking up to empire, bending the knee, being cordial, and being beyond cordial are about all they have for trying to get what they want out of this situation.
I think it's foolish. I think it's doomed to failure and the US is just going to come back again for another pass. But it's hard to say to your people that we must be the ones to fight the US empire when it seems like if you play your cards right you can get the empire, the eye of sauron to focus on another country and spare yours for a time, make someone else fight for you. And everyone has this idea so the US keeps getting concessions from everyone including the major powers because there's no desire to band together. There's no desire for pain and shared sacrifice. Too many people look back at the 20th century and Vietnam and Korea and are terrified into submission by those and Iraq. US may not win but you won't either. Your development will be set back decades, you'll endure horrific losses of civilian life, horrific lowering of quality of life. It was so much easier to resist when most people were peasants living very basic lives and had little to lose. Development has brought the trap of having far more to lose in a modern life if you challenge the empire.
Cell phone tracking. Facial recognition of those at the protest used via cross-reference with federal databases like state real ID photos most people get with their drivers license. Very easy. If you're not masked (and probably wearing big sunglasses) and not leaving your phone at home those are just two of the many ways they could do it.
But people post photos online of themselves too at the protest so there's always really low hanging fruit too.