Xiaomi normally has a decent reputation for keeping its phones updated with new versions of MIUI, its version of Android. However, the OEM has recently announced that some Redmi phones from 2017 or earlier will no longer be receiving this support. It means that these devices will see no further software development, although they may still receive regular security updates.
https://www.notebookcheck.net/Xiaomi-is-cutting-support-for-several-older-Redmi-phones.415878.0.html