343 Industries just dropped a teaser trailer on Twitter that suggests the Banished will play a significant role in Halo Infinite. The trailer is mostly audio, but the Banished insignia is clearly presented towards the end of the clip.
The Banished, led by the Joralhanae warlord Atriox, are a mercenary group that rebelled against the Covenant Empire. The splinter faction became a significant force at the conclusion of the Human-Covenant War.
For deeper insight into Banished lore, you can check out their Halopedia page.
Halo Infinite is expected to release later this year.