In Godzilla vs Kong Ren Serizawa (Shun Oguri) continues the MonsterVerse tradition of at least one character using the name Gojira instead of Godzilla. It's a way to both subtly honor the history and Japanese roots of the character and connect this Serizawa to his father, Dr. Ishiro Serizawa (Ken Watanabe) in the previous two films.
In the original Godzilla from 1954, the monster was first referred to as Gojira, which is an anglicized translation of the combination of the Japanese words for "gorilla" ("gorira") and "whale" ("kujira"). These were the qualities originally used to describe Gojira, as he was something massive that could both swim in the sea and walk upright on land. While Japanese kaiju movies still use Gojira to refer to the famous monster, when the first film was being brought over to America, Japanese production company Toho decided to change the name. They transliterated it to Godzilla, and in the rest of the world, the monster's gone by that name ever since.
When the first MonsterVerse movie, Gareth Edwards's Godzilla: King of the Monsters. In that film, he again referred to the kaiju by his original name and cemented their bond by sacrificing his own life in order to save Godzilla's.
Godzilla vs Kong continues this through Ishiro Serizawa's son, Ren Serizawa. Ren is the only major Japanese character in the film and the only character who uses the original Gojira name. This way the movie was able to carry on this tradition even with Ken Watanabe not being in the film. His feeling that someone should use Gojira instead of Godzilla allows the Monsterverse to continue to honor the legacy of Godzilla as a staple of Japanese pop culture, and one that they are still proud of to this day.
Yet, it also provides another connection to the original films, as Ren Serizawa is trying to kill Godzilla in this film with Mechagodzilla instead of protecting the King of the Monsters as his father had. This makes him closer to the Serizawa of the 1954 original, who sacrificed his own life to destroy Godzilla. Though it's adding to the mythology in a number of ways, the MonsterVerse is still steeped in the history of the kaiju films that came before and continues to work in various references into entries like Godzilla vs Kong to subtly honor that history.
