Both 雑 (ざっ, mixed) and 駁 (ぱく, mixed/disorderly) are On'yomi, with a small っ (促音便) for phonetic flow. It describes something that is disorderly, haphazard, crude, or unrefined in its composition or style. ざつぱく misses the necessary small っ.

雑（ざっ）と駁（ぱく）は共に音読みで、間に促音が入ります。内容がまとまりなく、ごちゃ混ぜで粗雑な様子を指します。ざつぱくは促音を伴わない誤読、そうはくは雑の誤読です。