I suppose it is effectively a rounding error unless you change the actual protocol.

I wouldn't be surprised if there was some trivial way for the manufacturers to add ultra low speed non-bluetooth data to the Bluetooth chips though, so you could have 2400 baud IDs with microwatts of power.

But it's probably not worth it since I suspect the real power drain on airtags comes from the high update rates and maybe the 2 way communication.