It should be noted that this should not work. In every version of the game I am aware of, the spell description for wish explicitly calls out wishing an enemy dead as something the spell should not be able to accomplish. The typical monkey’s paw that is described as happening when you attempt to wish a person dead is that you are propelled forward in time until after they die, effectively removing you from their lifespan. This is part of the 5e description of wish as well.

For example, wishing that a villain were dead might propel you forward in time to a period when that villain is no longer alive, effectively removing you from the game.

Vlaakith is an ancient and powerful enough lich that it is entirely reasonable she has the means to kill a low level adventurer like the protagonist of BG3, even from her safe stronghold on another plane of existence, however, the particular method they chose to have her do it in is explicitly called out as something that is impossible, and shouldn’t have been used, if only because it sets a bad example for people who have never played D&D and BG3 is their first experience with it.