Fixed or not, the one thing we know is that the league has ZERO transparency for their officiating program. And it is because of this that every bad call seems like a fix.
There is empirical data clearly showing that home teams and superstars get more favorable calls. The cause of this may be simple human bias that is subconsciously rooted, or something more deliberate and sinister.
My personal belief is that the officiating program has inadequate training, funding at the developmental level, and performance tracking. In addition, many of the long time referees have personal agendas against particular players and coaches, and there is no accountability to handle this.
The lack of accountability and transparency has led to the league officiating becoming extremely flawed. And such flawed results are not particularly distinguishable from if the games were fixed. So is the game fixed? Probably not, but the results are the same!