Smite damage too low

I have Netherite sword with Smite V enchantment. When I hit a zombie, it is expected to die in one hit, but it's not. Accordinng to the wiki info, it have to deal 21.5 damage at level 5 with netherite sword, but that's not entirely true.

So is this a bug, or is the wiki lying? What is real smite damage bonus?