Counterpoint: I've been using the Unsloth Gemma 4 quants extensively since very soon after release (on ROCm and Apple Silicon, I don't have any Nvidia hardware big enough), pretty much every quantization down to 4 bits (the QAT is the business, indistinguishable from the full-fat version, runs great on a slightly chonky desktop or laptop), and I haven't had any issues. The reason I use Gemma 4 so much often comes down to how reliable it is; when I want to experiment with llama.cpp settings, MTP, n-gram, etc. it's my go-to because I know there isn't anything wrong with the model or the quantizations that could interfere with the experiment.

It did take a little while for Unsloth to update the Laguna S 2.1 quants to fix the yarn_attn_factor, and so it was a bit frustrating getting that quantization running right, but almost always, I pick the unsloth quantization if there is one. (Still waiting/hoping for a Ling 3.0 Flash.)