No, unfortunately this is not some kind of a cool new feature or game mode that would somewhat benefit certain players. This is actually an error that many Call of Duty players have indeed spotted that with the new Maxis Bundle, some players are actually invisible in matches. Strangely, the weapons don’t seem to have been affected.
Treyarch have definitely taken notice of this and have confirmed that they will be “investigating & working on a new fix”. Charlie Intel have tweeted earlier that “The Maxis operator is only appearing invisible for players in their own POV. It’s not affecting gameplay or enemies.” and then they followed this tweet with an update, which is “The Maxis invisible bug is currently only affecting the Zombies mode. In MP, players are experiencing an issue where the operator may appear Adler instead. A fix is coming ASAP, and a workaround is to equip the Operator via the Bundle locker.”