The mod will partially turn off Epic Games integration, which prevents you from unlocking various Achievements. The mod in question is called ' Epic Games Patcher at Fallout New Vegas,' available from the popular modding site Nexus Mods. However, a workaround to mitigate that issue is to install a mod to the install directory (C:\Program Files\Epic Games). Fallout: New Vegas game version from the Epic Games Store doesn't support mods since it was listed on the popular marketplace.
This is because Fallout: New Vegas mods are not compatible with Epic Games Store, but it can still be achieved. According to a support FAQ page from Bethesda, you cannot officially mod Fallout: New Vegas game version currently available through the Epic Games Store. Is Modding Available For Fallout New Vegas Via Epic Games Store?
