is “dei” a slur or something?

so i was talking to a maga family member about one of my stories i was planning to make, which happened to have a diverse set of characters from different cultures and countries.

the family member responded by calling the characters “dei”? (diversity, equity, inclusion) is this a word that maga uses as a slur?

i don’t even get how having diverse characters is an insult. do they WANT every single character in everything ever made to be white or something?