pardon the ignorance but it's the first time I've heard of bfloat16.

i asked chat for an explanation and it said bfloat has a higher range (like fp32) but less precision.

what does that mean for image generation and why was bfloat chosen over fp?

My fuzzy understanding, and I'm not at all an expert on this, that the main benefit is that bf16 is less prone to overflow/underflow during calculation, which is a source of bigger problems in both training and inference than the simple loss of precision, so once it became widely supported, it became a commonly-preferred format for models (whether image gen or otherwise) over FP16.

Wiki article on bfloat16 for reference, since it was new to me: https://en.wikipedia.org/wiki/Bfloat16_floating-point_format