Samsung began the One UI Watch 4.5 beta program for the Galaxy Watch4 series a few months ago, and it seems the testing has gone smoothly since the company took to its community forums to announce the closing of the beta program, meaning the Korean conglomerate won't release any new beta builds for the Watch4 lineup. While Samsung didn't say anything about the release of the One UI Watch 4.5 stable update, some users have already started receiving the stable One UI Watch 4.5 on their Galaxy Watch4. Samsung Galaxy Watch4 The update comes with firmware version R870XXU1GVH2/R870OXM1GVH2...
Source: https://www.gsmarena.com/samsung_galaxy_watch4_galaxy_watch4_classic_one_ui_4_5_stable_update-news-55631.php