supposed to have and must have done

[ostap77]

"What’s LeBron supposed to have done wrong?"

OR

"What must LeBron have done wrong?"

What would be the difference?

 

[Raymott]

"What’s LeBron supposed to have done wrong?"

OR

"What must LeBron have done wrong?"

What would be the difference?

"Supposed to have done" means "Generally considered to have done." It's most likely that this is what he has done.

"Must have done" means it's the only possibility, not simply an inference of probability. (Actually it can be used for less than a 100% probability, but you're saying that you firmly believe that this is what he did.)