It was reported recently that Xiaomi had introduced the anti-rollback feature to Redmi 6 Pro models running MIUI 10 China Development ROM version 8.7.30 as well as models running the Stable ROM version 9.6.16 and above. Xiaomi has now announced the anti-rollback feature will now apply to Mi 6X models running MIUI 10 China Development ROM version 8.8.6 as well as models running the Stable ROM version 184.108.40.206 and above. The anti-rollback feature means users will no longer be able to downgrade their MIUI versions to older versions after the update.
According to the press release by Xiaomi on the MIUI Community forum, the new feature is to maintain system stability and ensure the security of the models. It is important to note if you own any of the two models that you will no longer be able to downgrade to earlier versions after the update as this could brick the device and render it useless.
However, if your model hasn’t been updated to any of the versions listed, then you can still use the rollback feature.