OnePlus is an OEM that has come to official ingress-protection ratings relatively late in its life cycle. However, it bowed to consumer pressure and provided the IP68 spec in its early-2020 flagship, the 8 Pro. Now, a reliable leaker asserts that its successor is getting the same.
https://www.notebookcheck.net/The-OnePlus-9-Pro-will-be-IP68-certified-whereas-the-9-and-9E-will-not.508881.0.html