This is a naive take. Are there specific instances involving individuals of many nationalities/ethnicities? Yes. Is ICE then ignoring race during its operations? Absolutely not. ICE agents are arresting people based solely on their physical appearance and accents. It is band faced racism.
It would be rather nonsensical to completely ignore ethnicity in your operations when the wide majority of illegal immigrants are going to be of that ethnicity. Obviously that would not justify widespread harassment of that group, but nothing like that seems to be happening. Mostly people seem to be trying to stop them from deporting people genuinely in the country illegally, which is divisive - independent of partisanship.
If the DNC has chosen this hill to die on, I don't think they're going to do anywhere as near good as they should do in November given Trump is engaging in some extremely unpopular and foolish behavior that people, again going beyond partisan lines, could easily rally together against.
If it was racism there would be extremely high false positive ratios. Is it observed?