Under false pretenses and under false pretences

Under false pretenses and under false pretences are two versions of an idiom that has been popular for about 100 years. An idiom is a commonly used word, group of words, or phrase that has a figurative meaning that is not easily deduced from its literal definition. Often using descriptive imagery or metaphors, common idioms […]
from Grammarist
https://grammarist.com/idiom/under-false-pretenses-and-under-false-pretences/