You're supposed to turn Bluetooth off when you don't need it – how risky is it?

On iOS is it really ‘off’? Surely it’s on at some level in order to widen the network for AirTags?

I always manually turn on/off whatever connection I (don't) need at that moment; bluetooth, wi-fi, cellular data

I mean, even if Bluetooth was completely safe, I'd still turn it off when it's not needed to save battery.