Evolution X is a custom ROM based on the Android Open Source Project (AOSP) that aims to provide a "Pixel-like" experience.
Even stable custom ROMs have quirks. For Evolution X on curtana:
No software is perfect. Here are the current known issues for Evolution X on Redmi Note 9s:
The Redmi Note 9s (codenamed Curtana ) was released in early 2020 as a budget king. Powered by the Snapdragon 720G and boasting a massive 5020mAh battery, it was a mid-range marvel. However, as time passes, Xiaomi’s stock MIUI (now HyperOS) becomes bloated, sluggish, and outdated. Security patches lag, and the interface feels heavy.