I was walking around in the nether biome and decided to randomly kill a Zombified Piglin (ZP) with my Smite V Netherite Axe, which instakilled the ZP, causing it to not anger. However, a normal zombie spawned, which I believed was a result of the "reinforcements" mechanic, since zombies normally don't spawn in the nether. I captured a screenshot of another instance of this bug on the nether roof where, after I fought some zombified piglins, spawned.