ICE leadership below the top level is currently being purged, and apparently replaced with officials transferred from Border Patrol,
because ICE’s approach and culture is more targeted and criminality based, and many of the biggest abuses so far in the immigration crackdown blamed on “ICE” have actually been carried out by Border Patrol (its not a coincidence that much of the current controversy in Chicago centers around thhe regional Border Patrol commander.)
While ICE is being massively scaled up with the intent that you describe, its not unique in kind or even the worst by degree of the agencies involved in terms of either historic or current lawlessness. It's just the one with the public mission most in line with the propaganda cover chosen for Trump's totalitarian efforts.