I'm still knocked down, but I up the ante
This line refers to how Donald Glover is still underrated and derided as a rapper, but is using that derision to keep putting out quality music that just gets better and better with each incarnation of his work.
It’s also a good example of a poetic/musical device called “word painting”, the choice of words matches the tonality of the music or inflection at that particular time.
Also an oxymoron.
Also “up the ante” is a poker reference. He’s saying people knock what he’s doing so instead of folding he raises the stakes.
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