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Here’s a summary of the Android Authority article:
OnePlus temporarily blocked downgrades to older software versions (from 16.0.2.50x) due to security concerns. This caused issues for users trying to downgrade or install custom ROMs, possibly bricking their devices.
OnePlus has stated that they will restore the ability to downgrade in their next regular software update. In the meantime, users who need to downgrade can contact OnePlus support directly.
The move was related to the introduction of Anti-Rollback Protection (ARB), a hardware-level security feature. OnePlus framed the temporary block as a measure to strengthen device security.
