The Brief: "Alphabet soup" is a slang nickname for the LGBTQIA+ community.

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In the same vein as alphabet mafia, the term “alphabet soup” references the letters in the LGBTQIA+ acronym. This playful label doesn’t have a particular connotation tied to it, and it can be found in both positive and negative contexts on social media.
LMAO SOMEONE CALLED LGBT “alphabet soup gang”
— hiba7am (@kokichidr) January 14, 2021
@horrrhaus let me in pleaSe #lgbt