Vernacular Venting & Semantic Solace
This is gospel
You so perfectly describes a feeling I've had all too often regarding the pronouns/ referent terms I may hear/ see in text messages.
I'll never forget walking to deliver lecture one day back in 2014 - wearing dress pants, shirt, tie, & a vest - and someone I knew remarked "You look so gangster today" ... like what about a general university professor's outfit triggered the term gangster? Obviously it wasn't the clothing.
Importantly, I think in casual interpersonal interactions this is more problematic the *more* you know someone. For instance, if you have a disagreement with someone & they suddenly - for the first time in entire history of your interactions with them - decide to use words like 'dawg, bro, sis, gangsta, homeboy, homie, etc' with you, it's an instance of vernacular venting.
To avoid being explicitly negative or saying anything supra-objectively offensive, they seek semantic solace by changing the pronouns they use to refer to you for the remainder of the conversation or an otherwise short window of time (it's unlikely to become their new normal/ permanent style in interactions with you).
As you said, definitely passive aggressive.