Lexus LC Hybrid Power Loss

The symptoms you describe, particularly the reduced power, jerking, smoke, and error codes, suggest a combustion issue. Have you tried using a higher fuel octane rating? Detonation or pre-ignition could be the cause, especially if the error code relates to ignition timing.

I usually just fill up with regular fuel. What kind of octane rating should I be using? Could this be something worse, like piston slap?

While higher octane fuel might help if the issue is minor detonation, piston slap is unlikely given the hybrid engine's characteristics. Deposits in the combustion chamber are a more probable cause. I strongly recommend having a workshop investigate this as soon as possible.

Thanks for the advice. I took it to a local shop, and they confirmed deposits in the combustion chamber. They cleaned it out, and the car runs like new again. Cost me 425€.