Hmm...idk...I'm glad more people are opening up to her vocal prowess. I don't know if I'd say she's trying to prove something vocally or if she just likes trying new things, or maybe that's bits of her perfectionist showmansip leaking out.
Judging from that reply section, there's a lot of backhanded compliments to Brandy. It's like people can't say how dope she is without :criticizing or pointing out her weaknesses, comparing her to other singers, or comment how undeserving it is for "the fans" to call her the vocal bible.
I notice that people tend to not do this on the other videos on that series for Jazmine or Keke Wyatt, singers that are easily accepted as vocal beasts.
If Brandy is "doing too much" vocally then I don't see what approach she should take to convince people otherwise, assuming she cared.