It's possible that they were indeed copying the question to an LLM each time, or sending it to a tutor via some chat, and then answering afterwards.
But it's also possible that a Windows Update notification popped up asking to restart the computer, coincidentally, 125 times (or some other application). This makes it hard to punish the student from just leaving the exam page.
And students can easily cheat by using a different computer or a phone to search for solutions, you'd never find that out from the quiz log.
Take-home exams were always easy to cheat on and hard for professors to stop. LLMs just democratized access to cheating (before, you may have needed a paid tutor to help).
I'd say this makes the current era significantly more "moral" than 5 years ago at least in the sense of fairness between students, and the students are not any more "dishonest" than they were 50 years ago, they just have easier access to cheating choices.
Third party solutions like LockDown Browser may help, but the only real solution to stop cheating is having in person exams, perhaps on paper (or on computers with a monitoring software, but still in person).