Yet Trump did not accept to change it when he could.

So on these two options:

a) by mere effect of magic (just like Trump "won" the elections but lost the elections) the immigrants have become criminals, but only the last four years.

or maybe...

b) they are still less criminally active that the average US citizen and the argument about them is a lie that has been used during the last four years.

What seems to you like the most likely explanation of these two??

The fact is that it is very easy to see a criminal that is undocumented make the news, it is very easy to cast the prejudice and it is particularly easier because there has been certainly an increase in crossings - inevitably, plain numbers are going to be up. But if you look to percent as a measure of honesty, immigrants are rising the bar of the existing citizens. They are less criminal than US citizens.