My D1x Procharged 2019 Camaro SS on e70-e85 on 6 psi CEL started flashing in 4th or 5th gear at around 6000 rpm.
I did a quick check to see if there were any misfires because i was always told that the CEL flashes when there is a misfire. To my surprise a found no misfires, only these codes

P0121- has been thrown before when letting off in the middle to top end of a full pull, but usually goes away within 4-10 ignition cycles.
U0100- this is unknown to me. It says "lost connection to ecu" I know absolutely nothing about this code, what would cause it, or how to check it, or how to fix it. Does anyone know anything about this code?