OnePlus has Already released OxygenOS 12.1 OpenBeta 1 for OnePlus 9RT. So before Releasing Stable OxygenOS 12.1 Update, OnePlus Released Maybe the final build of OxygenOS 11.3 with June Security patch and System Changes.
OnePlus 9RT OxygenOS 11.3 A.11 IND
• Fixed the issue that the call recording option could not display
• Optimized network stability
• Improved system stability
• Updated Android security patch to 2022.06
• Fixed the occasional issue that camera crashed abnormally