You’re trying to defend yourself using Wiktionary but didn’t include the full meaning:
From bean + -er. Literally "a person who eats beans".
Beans are a staple of Mexican cuisine.
Noun beaner (plural beaners)
- (US, ethnic slur, offensive) A Mexican.
- (US, ethnic slur, offensive, by extension)
- Any Hispanic person.
(sometimes offensive, slang) Used as a casual term of address to a friend or acquaintance, especially used by Mexican Americans.