Answer:
out of scope modification
Step-by-step explanation:
Based on the scenario being described within the question it can be said that this mistake is known as an out of scope modification. This term refers to a change that is done to fix the immediate and visible problem but at the same time causes other problems to arise that were otherwise not visible (bigger picture problems). Such as in this case since Becky made the changes to fix the errors that she found but did not realize that these "errors" were connected to various other parts of the data, which caused bigger errors to occur.