Is reverting to Oxygen OS A16 as simple as flashing the latest OP12 OOS zip file using Lineage Recovery?
EDIT: I tried flashing OOS CPH2581_16.0.3.500(EX01) via Lineage Recovery, but the install aborted. Is anyone able to help me get back to Oxygen OS 16, so I can get to fix my FRP issue?
sorry, i donāt know OnePlus devicesā¦
Notes this informations can be outdated, please improve them
Often worth to check the Lineage pages.
This is not your solution Update firmware on waffle | LineageOS Wiki but I learn from there that Release v7.0.0 Ā· oxygen-updater/os-updater Ā· GitHub is updated.
Maybe this allows you to find a Fastboot ROM (references do not appear in @pieroās link above, as user results were negative with original versions).
Hereās what worked for me, albeit with a minor issue or two.
I used LibreFastbootFirmwareFlasher + CPH2581_0.3.500(EX01) from the dynamic link provider at Daniel Springerās website (LINK). That got me back to the OP12 OOS 16 Global ROM.
The only issues Iām experiencing are that my credit card isnāt loading properly into Google Wallet and OnePlus Camera app crashes continuously. Might be because my device is actually CPH2583, not CPH2581. Might play with this a bit before installing e/OS/ again after properly removing my Google Accounts.
I have to say OnePlusās ripoff of iOS glass theme is seriously ugly. Not sure what focus group that had that let that pass through, but yikes 
for anyone having this in the future, before reverting to stock, Iām curious if you have in the recovery (via enabling in adv. options) the adb subcomand
available. LineageOS derived recoveries have it. You can also push the shellscript to the recovery /sdcard and execute there if itās a earlier build then a16 / 23.2.