"Unforeseen consequences" refers to unexpected outcomes or results that occur as a result of certain actions or decisions, which were not anticipated or predicted beforehand. Full definition
This demand surge has caused unforeseen consequences for the environment. (livescience.com)
A program that allows borrowers to have their student loans forgiven for entering into a public service career could come with unforeseen consequences. (studentloans.net)
This immensely complex piece of legislation will have many unforeseen consequences that we are only now beginning to comprehend. (lawyer-monthly.com)