Unidentified cause of quantization degradation spike in Amber-7B

Identify the underlying cause of the sudden increase in 4-bit post-training quantization-induced degradation observed in the Amber-7B model despite the quick recovery of full-precision validation loss during training.

Background

In the appendix, the authors examine additional model families and note that Amber-7B exhibits a brief spike in full-precision validation loss that quickly recovers. However, 4-bit GPTQ quantization degradation rises sharply and remains elevated.

This anomaly suggests a change in training dynamics whose cause the authors explicitly state they cannot identify, making the underlying driver of the quantization spike an open question.

References

While the full-precision model quickly recovers, 4-bit quantization degradation rises sharply, hinting at a change in the training dynamics whose cause we cannot identify.

— Training Dynamics Impact Post-Training Quantization Robustness (2510.06213 - Catalan-Tatjer et al., 7 Oct 2025) in Appendix, Section “PTQ robustness on additional models in the wild” (Section \ref{wild:all})