It seems you are encountering an issue where your Poco X3 Pro is unable to update to a newer version of MIUI. This could be due to several factors. Below are the steps to troubleshoot and potentially resolve the issue:

1. Check Account Permissions:

   • Ensure that your Mi account has the necessary permissions. Some ROMs may require a Mi account with special permissions, especially if they are beta or developer ROMs.

2. Verify ROM Compatibility:

   • Double-check that the ROMs you downloaded are specifically for your device model (Poco X3 Pro). Incompatible ROMs can cause the error message you're seeing.

3. Unlock Bootloader:

   • If your bootloader is locked, you may need to unlock it before you can flash a new ROM.

4. Use Official Sources:

   • While the Xiaomi Firmware Updater website you used is known to provide legitimate ROMs, it's generally better to use the official Xiaomi MIUI website or the Mi Flash Tool to find and install ROMs.

5. Use Xiaomi PC Suite:

   • Xiaomi’s official PC Suite software can sometimes troubleshoot and install updates that the phone itself cannot.

6. Factory Reset:

   • As a last resort, you might consider performing a factory reset. Ensure that you back up all your data before proceeding with this step.

7. Contact Xiaomi Support:

   • If none of the above steps work, consider reaching out to Xiaomi's customer support for further assistance.

Each step represents a potential solution to your problem. Remember to back up all of your data before attempting any steps that could erase information on your device.

It's time to switch to Stock Android.