Apart from the theatrical release, there is not a single other release out there that treats "The First Kiss That Never Ends" as a single episode, but rather as 4 individual episodes.

Just because a series of episodes is shown in the cinema as one episode, they should not be treated as a movie.

It is also listed on crunchyroll as its own season instead of as a single movie as can be seen here in the season selection. (S25: Kaguya-sama: Love Is War -The First Kiss That Never Ends-) https://www.crunchyroll.com/series/GRJ0J828Y/kaguya-sama-love-is-war

The televised broadcast and streaming release of the movie is divided into 4 parts. So it would be correct to list it as a TV show with 4 episodes or as an extra season in the already existing entry of the series. In this wiki article you will find the episodes presented correctly: https://en.wikipedia.org/wiki/List_of_Kaguya-sama:_Love_Is_War_episodes

The correct entry would be a series or season with the following episodes:

• E1 - Miyuki Shirogane Wants to Talk Things Over / Miko Iino Wants to Talk / About Kaguya Shinomiya, Part 3
• E2 - About Kaguya Shinomiya, Part 4 / Kaguya Wants to be Noticed (Ice) / Kaguya Wants to Forgive (Ice)
• E3 - Kaguya Wants to Eat It (Ice) / Our Persona /Kaguya Wants to Confess (Ice)
• E4 - Kaguya is Fine With It

Many thanks for your effort!