The Entertainment Software Rating Board has revealed its rating summary for Fallout 76 Wastelanders. The expansion ended up with a Mature rating due to contents categorized as Blood and Gore, Drug Reference, Intense Violence, Strong Language, Suggestive Themes as well as Use of Alcohol. You can find the full ESRB description below:

This is an open-world role-playing game in which players must survive/thrive in a post-apocalyptic world. From a first- or third-person perspective, players search for supplies/food while battling other survivors and mutant creatures. Players use machetes, machine guns, rocket launchers, and grenades to kill ghoul-like creatures and other enemies in frenetic combat. Some weapons allow players to blow ghouls apart, resulting in flying limbs and chunks of flesh; wounded characters can also be executed with gunshots to the head, resulting in decapitation. The game contains some suggestive material in the dialogue: “I’ve got a button-shaped bruise on my backside after that last romp on the console”; “Nothing brings me down to Earth like making love to you on the cold, hard ground.). The game includes frequent references to drugs called Chems, which are sometimes used as plot points for characters; Chems can be found, manufactured, and used to enhance performance/skills of characters, though there is no actual depiction of use. A handful of story missions require players’ character to acquire ingredients to make alcoholic beverages; one alcoholic drink (Nukashine) can cause the screen to blur and/or discolor after being consumed. The words “f**k” and “sh*t” appear in the dialogue.