While the Galaxy Note8 has started receiving the stable Android Pie, its mates Galaxy S8 and S8+ are also moving towards the stable build, as both of these devices are now receiving their fourth One UI beta update.
The new update brings fixes to multiple bugs occurred in the previous One UI beta rollout, the update also brings February 2019 security patch (same as the last update). Please check the full changelog in the screenshots linked below.
The update is currently rolling out with build version G950FXXU4ZSB9 and G955FXXU4ZSB9 for the Galaxy S8 and Galaxy S8+ respectively. You can also check for the update manually by heading into the Settings > Software updates.