Batching doesn't mean the computation suddenly becomes non-deterministic. Ideally, it just means you perform the same computation on multiple token streams in the batch simultaneously, without the values interacting with each other. Vectorization, basically.

Batching leads to cross-contamination in practice because of things like MoE load-balancing within the batch, or supporting different batch sizes with different kernels that have different numerical behavior. But a careful implementation could avoid such issues while still benefiting from the higher efficiency of batching.