Prior to Borderlands 3's launch, Gearbox gave out Vault Insider Program keys that worked similarly to Shift Codes. You earned them by doing things like watching trailers or following its social media.
Based on the appearance alone, this Vault Hunter may be similar to either Borderlands 3's Moze or Borderlands 2's Gaige, with the archetypes in question being the Gunner and the Mechromancer.
Borderlands 4 is coming out in 2025, and now is a good time to check the whereabouts of every playable Vault Hunter in the series.