https://wccftech.com/galaxy-s9-s9-get-their-fourth-android-pie-beta-update-in-the-uk-and-germany/

One can rightfully argue that Samsung’s Android Pie rollout is late compared to the competition. However, the company has been doing an excellent job of trying to bridge the gap and a few years down the line; we can expect to see Samsung update their devices alongside companies such as OnePlus. The ongoing Android Pie beta program for the Galaxy S9+ and S9+ is presumably in its last phase as its fourth iteration is rolling out today to some users in Germany and the UK.

This is good news, as the original Android Pie beta was in a state of near completion after four iterations. We can expect a full-scale rollout by January next year, as promised. The primary purpose of incremental updates to a beta build is to quash bugs introduced by a previous release. Since it is a beta, the initial builds are a broken mess which gets better over time. Samsung is engaged in a never-ending game of whack-a-mole with their software and some issues persist even through the final release.