This is the first time I’ve seen this one. Best result I saw from 30 seconds of googling:

In 2020, the National Runaway Safeline (NRS) began using LGBTQIA2S+ to recognize those who identify as “Two-Spirit.” This phrase refers to people who identify as having both a masculine and feminine spirit, and is used by some Indigenous and Native communities.

“Two-Spirit” describes the cultural-specific understanding for the diverse gender traditions of Indigenous and Native people. Historically, Two-Spirit people were among the most respected in their communities, often serving as community healers, ceremonial leaders or caregivers to the elderly or orphaned children. This is consistent across many cultures who experienced extreme oppression and intergenerational trauma through periods of colonization. Today, young people who identify as Two-Spirit may suffer from inequalities perpetuated by a legacy of discriminatory laws and policies.
Source: National Runaway Safeline

From the article:

I'm using LGBTQIA2S+ as a shorthand for lesbian, gay, gender non-conforming, genderqueer, bi, trans, queer, intersex, asexual, agender, two-sprit, and others (including non-binary people) who are not straight, cis, and heteronormative. Julia Serrano's trans, gender, sexuality, and activism glossary has definitions for most of terms, and discusses the tensions between ever-growing and always incomplete acronyms and more abstract terms like "gender and sexual minorities". OACAS Library Guides' Two-spirit identities page goes into more detail on this often-overlooked intersectional aspect of non-cis identity.

A terrible idea by the LGBT community to expand the definition, when they thought they already "won" the battle and wanted to expand their scope, completely ignoring how marginalized the trans community was at that point, and how much was still left to fight for LGB rights. People quickly objected and most threw away the dumb acronym.