: Uninstall unused apps and use the "Force Stop" feature for apps you rarely use to free up RAM.
OPPO support has stated that because the model was launched in 2019, its hardware performance is insufficient to support the requirements of ColorOS 12 and Android 12. oppo a9 2020 coloros 12 update
Custom ROMs: The developer community sometimes creates unofficial ports of Android 12 or 13 (like Pixel Experience or LineageOS) for older devices. This requires unlocking your bootloader, which voids your warranty and can be risky if you are not tech-savvy. : Uninstall unused apps and use the "Force