I check for it, but I haven’t seen anything like you’re showing in a long while. That’s odd. Usually the issue I see with ERG mode and using the big ring is set-point accuracy responsiveness (how long it takes to stabilize), not power accuracy per se.
In your case, having a left-sided only unit makes it tricky to know for certain.
Note that while some trainers do still struggle with high flywheel accuracy issues, but for the most part I see that more in SIM mode than ERG mode. Most of my ERG-related high flywheel issues are around set point responsiveness/accuracy.