A report concluding that Saudi Arabia likely hacked into Jeff Bezos’ smartphone has spurred questions and confusion among cybersecurity experts, even as it has prompted renewed scrutiny of the kingdom and its crown prince.

Cyberforensics specialists said the report, which is dated November 2019 but didn’t surface publicly until this week, relied heavily on circumstantial evidence to make the case that a WhatsApp account associated with Saudi Crown Prince Mohammed bin Salman was probably used to hack into the iPhone of Mr....