I am assuming you have the Bridgestone tyres fitted from the factory then ?.
One member HAS already switched out the factory tyres

to Michelin Cross Climates instead.
He reported that the new tyres, produce a LOT less road noise than the Bridgestones, and that the car now is pretty much silent.
Personally, I was disappointed to see that the S5 had Bridgestones fitted from the factory myself.
I have experienced Bridgestones on one of our previous cars and I absolutely hated them with a passion.
The traction was poor and they produce a lot of road noise and drone, compared to the Good Years I replaced them with.
The noise level and poor traction will only get worse as they wear down also.
The difference between the tyres, was night and day tbh.
I do find that when you are cruising at about 56Mph in the S5, there is a presents of a dull “drone” in the cabin on these Bridgestone’s.
It was the same noise we had on our previous car.
Honestly, I think you have made the correct decision to switch them out.
Not really what you want to do on a car that is almost brand new, but otherwise you are going to be stuck with the problem for the next 20,000+ thousand miles
( depending on your driving style etc ).
If you only cover average miles / year, you are going to be stuck with them far TOO long.
I have to say, that I have seriously contemplated switching mine out also.
I am puzzled why a manufacturer would fit these tyres

to an EV ??.
In a ICE car there are other back ground noises that can disguise some tyre noise, but not in an EV !.
It just depends on what deal the manufacturer can get on a huge batch of tyres really, simply down to cost !.
If another tyre company offers them a better deal, then they will switch in a heart beat.
If you do go ahead and switch them out, please let us know what you went for and how do the new tyres compare to the original Bridgestone tyres

.