[Certain]

I don't want to make this about your voice, since you said not to, but I think it's important to write to your own voice. Your annunciation isn't great when your assonance or rhymes get too heavy. Perhaps stripping down a bit on that end of the complexity would make it a bit easier to understand. Then again, that echo effect may be the biggest culprit.

I also thought you pronounced words strangely a few times simply to get the rhyme. The advantage of rhyming off the same sound for an entire verse is much more evident in text than on audio, so don't be afraid to switch up. Besides, you already had a whole bunch of pauses (which I didn't care for because they were so numerous) where the rhyme switch would have been very natural.

Edit: I actually liked this a lot. Your wordplay translated better than I would have expected, though having a lyric video definitely helps that. I thought "wiping away the dirt poor like Oxyclean" was probably the standout line. So there's no reason to go writing another whiny diss verse about how people criticize you. You're very, very good. The criticisms come out harsh because we all know that and know you know that.