The leaker claims that they've seen the Swastika in a mission of COD Vanguard's campaign. This was an unknown aspect of the game heading into launch, as developers in the past have avoided using the Swastikas for obvious reasons. However, some fans argue that this takes away from the immersion as it's not realistic.
Either way, it appears that Sledgehammer Games is giving players the option to see Swastikas in COD Vanguard or not see them.
COD Vanguard's toggle Swastika feature

The insider in question is Call of Duty leaker @TheGhostOfHope. They have a sparkling record of leaking information before its official release regarding the COD franchise. In a recent tweet, they claim that Vanguard has Swastikas in the campaign.
TheGhostOfHope states that "you can enable Swastikas for the Campaign in Vanguard." They followed up by saying they've seen the same scene but with an Iron Cross in place of a Swastika. The Iron Cross is the default logo developers have used in previous World War II titles to avoid the Swastika controversy.

It's worth noting that the leaker mentions you can toggle the Swastika on and off. Being able to enable it in the campaign is great for players who want a completely realistic experience but allows players who don't want to see it an option to disable it.
In the past, Call of Duty stayed away from using Swastikas in their games due to the German government banning any game with the logo featured in it. However, Germany lifted this ban in 2018, so Activision and Sledgehammer Games are safe on that front.
The option to disable the Swastika in Vanguard likely boils down to giving players a choice on what they see in-game.
Call of Duty: Vanguard releases on 5th November for all major systems.
Don't forget to check out our dedicated Call of Duty section for Vanguard news, loadouts, tier lists, leaks and much more.
Featured image courtesy of Activision.