The July 2021 security patch for Samsung phones fixes 3 critical and 38 high levels of Common Vulnerabilities and Exposures (CVE’s) that improve system security. As of now, we do not have the complete changelog for the new build, but it is likely to bring some additional improvements or features, in addition to the July 2021 security patch. As mentioned earlier, the new update for Samsung Galaxy A51 is currently rolling out in Russia. But, we can expect it to reach other regions over the next few days. In the meantime, you can manually update your phone by navigating to Settings » Software updates and then tap on Download and Install.
Samsung released the Galaxy A51 back in 2019 with Android 10 on board. This year, it received the first major OS upgrade, Android 11. As per the company’s software update policy, the Galaxy A51 will also receive the next major OS upgrade that is Android 12. [source]