It's all Freddie! His voice did change since being ill. I believe it is 100% Fred!
I agree...his voice does sound different on Innuendo, and you can definitely tell the newer tracks on Made In Heaven from the older ones that were reworked
But, in my opinion (and this is just my opinion), his voice sounded better on Innuendo than any other album...I'm always awestruck when I listen to it to know he could still hit those notes as ill as he was when there's performers today, like Elton John, who can't hit the high notes anymore