I need help please about being accused on cheating
He sent me an email to discuss, and then during the online meeting, he asks me to do an oral exam.

You present this as a bad thing, but it's actually a good thing.
Apparently you did all the tests unusually fast, and in a way that looks to an observer like you're cheating. But that's not enough proof. It's possible that you're just pretty good at this subject. So the professor needs to test whether you cheated or whether you're just really good and fast at this subject.
That's what the oral exam is for. If you know this subject really well, you should also be able to do well in the oral exam.