A defective set of spark plugs with certain model year 2023 Toyota GR86 to have premature failure. While driving at highway speed spark plug blew up resulting in a cylinder 4 misfire and loss of drivability. The service advisor from the Toyota dealership unofficially confirmed this has happened to multiple other gr86 models. Along with being unofficially confirmed by an aftermarket specialist. Original diagnostic from the dealership was to replace the motor due to all of the issues, while a local certified mechanic has replaced the spark plug, coil pack, and is continuing to troubleshoot as the head gasket also needs to be replaced. No warnings lights or signs were present prior to failure.