Keras Mixed precision on AMD GPUs results in lower performance

I've noticed a few things when trying to run Keras 3 with a 9070 XT and ROCm 6.4.2:

Setting keras.mixed_precision.set_global_policy("mixed_float16") reduces performance. Setting keras.mixed_precision.set_global_policy("mixed_bfloat16") does not, but it doesn't result in a performance uplift either.

I see there's a similar issue open: https://github.com/keras-team/keras/issues/18885

I just want to confirm that this is still the case.