I think they installed the UI8 Beta with a third party app or device. U8 Beta is available only for S25 Series now, not even for Tab S10 Series is not available.
Unless you want the Beta for testing and feedback, there is no point to use Beta. Beta software is to test if there are bugs and how you get along with the look, etc. Some functions of the phones will not work, some will be buggy. Better to wait for the stable version. Using Beta of a software it doesn't mean you get thr software before everyone else.
Your phone has UI7, or should have already, since May.
If not, download update your phone to the UI7. They are not much different. With One UI8 they will just fix some bugs, maybe ad a feature or two extra, change some icons and that's it.