Today, Microsoft is releasing a small update for Insiders on the Release Preview ring that are on 19H2. Remember, the Release Preview ring is on two separate paths, 19H1 and 19H2. Interestingly, both paths were supposed to be receiving the same bits, except the 19H2 users got an extra package to make it 19H2.
This update was released for those on the 19H1 path on Wednesday. It's unclear what's changed about the update since then. Today's build is 18363.387 (the 19H1 build is 18362.387), and the only changes should be some fixes for uninstalling 19H2 updates.
Being that the version number for this update will be 1909, it should be finalized any day now. But there's still a lot that needs to happen before it's released to the public. The build number needs to align with the Slow ring 19H2 builds, which are all 18362.100xx, and Release Preview should be combined into a single path.
19H2 is going to be a minor update though, so there presumably isn't a lot of work that needs to be done. Hopefully, we'll find out more news about the update next week.