Indeed, the blowup of the singular quadric embeds into the blowup $X$ of the projective space, that can be alternatively described as $$ X = \mathbb{P}_{\mathbb{P}^2}(\mathcal{O} \oplus \mathcal{O} \oplus \mathcal{O} \oplus \mathcal{O}(-1)). $$
Indeed, the blowup of the singular quadric embeds into the blowup $X$ of the projective space, that can be alternatively described as $$ X = \mathbb{P}_{\mathbb{P}^2}(\mathcal{O} \oplus \mathcal{O} \oplus \mathcal{O} \oplus \mathcal{O}(-1)). $$