I'm Peruvian and married to a Colombian and have never heard of this. On the other hand, right across the Hispanic world it's very common to use @ for gender neutrality: nosotr@s, latin@s, etc.
That’s not surprising, since it’s purely a product of “woke” culture in the USA, and the only people who use it are either multiple generations removed from their “ancestral” country, or have degrees in social sciences from Ivy League universities (or both).
What's the proper pronunciation for those words?