The OnePlus 9 Pro has been shipping to people for about a week now, following its elaborate launch and extended marketing campaign. There are already countless complaints from people about their OnePlus 9 Pro handsets overheating, such as recording 4K videos or merely taking photos. OnePlus has already claimed that it is investigating the issue, but it is not a good start for the OnePlus 9 Pro.
https://www.notebookcheck.net/OnePlus-9-Pro-owners-complain-of-crippling-overheating-issues.531423.0.html