After the backlash OnePlus received due to the removal of the always-on display feature on its OnePlus 6, the company has said that it will be bringing it back with Android P beta, sort of. As you can see, the OnePlus employee didn't say that the feature will be included in the next major update for sure. Probably the company will be carrying out some tests in the Android P beta and then optimize it for less battery drain once the full release comes out. OnePlus 6 always-on display feature before removed In the meantime, the developers' team is working on another short-term OS...
Source: https://www.gsmarena.com/oneplus_may_bring_back_the_alwayson_display_feature_in_android_p-news-31378.php