Also, near the end of the game, I expect losing teams to commit more fouls, giving up free throws to prevent their opponent from using up the shot clock time.
”observe the videos of that game from different angles”
Ideally, you would process the video so that you can’t see who the players are or which team the player is on. I fear that isn’t possible, though. Experts likely will recognize players from their length and the way they play.
Perhaps the actual calls from the other game videos are used as a reference, such as whether a mere hint of wind-up is enough to score as such, or if the pull-back has to be very clear. Since different refs may have diff interpretations, perhaps the ref's history should be used as a guide. After all, the key question is about whether a specific game or season is "fixed", not all games from a given ref. If a ref has say 3 years of requiring mostly clear wind-up motions, and they were consistent on this during the target game, it probably wouldn't be considered an oddity.
Sure, that's a lot of digging and a lot of work, but if a play-off conspiracy has potential merit, it's worth it.
Nor is a single bad call evidence of bias, such as the nosebleed incident.
An example of a good evaluation would be several professional referees, not employed by the NBA, observe the videos of that game from different angles, and score the accuracy and fairness of each call and potential non-call, including which referee made the call and/or was closest.
I don't wish to accuse people of conspiracies without strong and detailed evidence. And, too many teams habitually blame the refs for bad results to deflect their own shortcomings as a team. I've heard "wolf" far too many times.
There is human error and thus randomness in referee calls. But as they say, luck favors the prepared. If you don't want bad calls deciding the game, then get good enough to have the margin of error in your favor.