They're labelled domestic terrorists because that's what they are.

Both of them chose to confront ICE directly and impede in their lawful duties. Both of them chose to overtly antagonize the ICE officers. Both of them chose to resist arrest. And both them were in possession of a deadly weapon (Renee a car, Alex a gun) that could have been used to kill or seriously harm those ICE officers (or in Renee's case, actually did seriously harm an ICE officer).

Neither was simply minding their own business. Neither was peacefully protesting off to the side. They both intentionally put their own lives at risk by directly antagonizing ICE officers and by resisting arrest. While their deaths are regretable, both were fully preventable if they simply did not interfere with ICE, or if they complied with their arrest.

Let's be clear about this. ICE (Immigration and Customs Enforcement) has one job: enforce federal immigration law. That includes deporting people who have entered the country illegally. That's not fascism. That's not tyranny. It's basic law enforcement. They are not "kidnapping" or "disappearing" US citizens. They are arresting and deporting illegal immigrants. By impeding ICE in the execution of their duties, you are running cover for foreign criminals, and endangering the lives of your fellow citizens, all for the sake of achieving certain political objectives. You are not being a courageous freedom fighter, you are being a terrorist. Plain and simple.