Tutorial how to get Global firmware version on your Mi Band 8
First, download and install the Notify for Xiaomi app from the Playstore
Once you installed and paired your Mi Band 8 properly on the Notify app, go on Tools -> Update firmware section
Download and save on your phone the global firmware version from any blog, or get it directly from:
Choose Firmware button and select the downloaded firmware to start to upload it into your Mi Band
Be sure to select the proper firmware version, the linked firmware is valid only for Mi Band 8, not Mi Band 8 PRO