The phrase "to become an issue" means to cause a problem or raise concerns. It can also refer to something that is important, relevant, or worth discussing.
Sentences with «to become an issue»
They typically only become an issue in hotly contested proceedings, when spouses can't agree on custody terms and their inability to do so forces the court to decide. (info.legalzoom.com)
It really does become an issue of gender politics. (health.com)
Cost can only become an issue if you have bad consultants and get stupid advice. (thefutureofpublishing.com)