This will likely bring the cost below 2.5 flash-lite for many tasks (depends on the ratio of input to output tokens).
That said, AA also reports that 3.1 FL was 20% more expensive to run for their complete Intelligence index benchmark.
The overall point is that cost is extremely task-dependent, and it doesn’t work to just measure token cost because reasoning can burn so many tokens, reasoning token usage varies by both task and model, and similarly the input/output ratios vary by task.