The answer to that question is complex and, generally speaking, it is safe to use. Google employs encryption in Meet that helps keep any information you might share secure. Anyone who has the Google Meet invite code must request permission to join the meeting and must be approved by the host first, so there is no need to worry about people who might acquire the code joining without permission. But one should also be aware that, even if there are these kinds of precautions in place, there is always a chance that someone might be able to access it even with those safety nets in place.