That gurgling sound is likely the water in the bath's p-trap bubbling as your toilet flush looks for air to properly drain the waste to the sewage line.
Flush the toilet a few times and the gurgling may stop. That's because the P-trap is now empty of water...proof? Pour water down the bath drain anf flush hte toilet again ... gurgles again?
If it has to pull air from the bath's p-trap the drain vent may have become clogged in the process of working on the bath drain.
Why did I post this?