QAT variant of Gemma4 26B A4B is not working well for me

In three linesUser reports that QAT variant of Gemma-4 26B A4B (google/gemma-4-26B-A4B-it-qat-q4_0-gguf and unsloth/gemma-4-26B-A4B-it-qat-GGUF:Q4_K_XL) produces degraded results on a chessboard SVG test with llama.cpp b9549, compared to the older non-QAT version which performs correctly.

Summary generated by Claude — human-verified