Download MIUI V18.104.22.168 Stable China Recovery ROM for Xiaomi Redmi K30 Ultra from here.
Archive name: miui_CEZANNE_V22.214.171.124.QJNCNXM_1ae9faa171_10.0.zip
Xiaomi Device name code: cezanne
Archive size: 2.8 GB
Android version: 10.0
Optimized system performance
Improved system security and stability
Caution Please do not update firmware unless you know what you are doing, you really want it or it is absolutely necessary. Firmware updates may occasionally have bad results, like bricking your device, temporarily or permanently. The firmware update process is done entirely at your own risk. Before attempting to update the firmware, back up your data.