Just a few days ago, OnePlus pushed a rather big update to the OnePlus 9 series addressing some software, camera and battery issues. However, it seems that the update to OxygenOS 11.2.6.6 didn't go so well for the OnePlus 9R and caused some battery drain problems. The hotfix to OxygenOS 11.2.3.3 seems to address just that. The changelog is pretty short but it also vaguely mentions that the patch solves a known issue. Sounds like a minor bug has been squashed. Anyway, OnePlus says that the rollout is incremental and it would take some time to reach all OnePlus 9R units. The file...
Source: https://www.gsmarena.com/oneplus_9r_receives_a_hotfix_for_battery_drain-news-49475.php