They have stopped some abductions, slowed the pace, made it require more manpower.

Lots of reasons they might burn waymos. I cannot care.

Waymo records everything, and has been used to arrest people after police requested data.

Well it also could be because waymo is owned by Alphabet (Google's parent company) and the side against ICE is also going to be generally against megacorps that are actively trying to sprint towards technofacism. But honestly I doubt that much thought went in to it. People are angry for a million different reasons in this country right now, and at a protest like this that is spontaneous (as opposed to organized/planned) that anger is bound to manifest in ways that aren't always the most productive to the cause. That's just human nature imo. Emotions aren't always rational. And sure, it's definitely possible this was an opportunist just looking for an excuse to be destructive, or even planted fed agitators like others have said, but if you ask me it's just as likely it's just some pissed off people who are just saying to themselves "fuck it, the government wants to fuck our shit up? Well then i guess we can fuck shit up too."

Editing to add: It can be hard to put yourself in their shoes if you've never been to a protest that got a little ugly, because you might imagine yourself in the same state of mind you are in as you're just like sitting at home or wherever reading this thread. But likely these fire starters have also already been tear gassed, shoved around by cops, corraled like animals, flashbanged, had rubber bullets shot at them, and all after watching fascist federal agents come in to their community and effectively dissappear people who are some of the most vulnerable among them. Maybe even close friends or family. It's honestly surprising how many are still able to maintain their cool enough to be peaceful after suffering all of that.

It may not have been protestors. The FBI is known to send in people to protests to cause trouble so law enforcement has an excuse to escalate.

When trying to fathom a complex plot, look at who benefits.

Who benefits from senseless property destruction where nothing of value is stolen and the target poses no threat?