Unless the plan is to quickly produce a prototype that will be mostly thrown away, any code that gets into the product is going to generate far more work maintaining it over the lifetime of a product than the cost to code it in the first place.

As a reviewer I'd push back, and say that I'll only be able to approve the review when the junior programmer can explain what it does and why it's correct. I wouldn't reject it solely because chatgpt made it, but if the checkin causes breakage it normally gets assigned back to the person who checked it in, and if that person has no clue we have a problem.