Right-mouse click the game in your Steam Library
Go to Properties
Under the General Tab, look for Launch Options
Enter in the following command:

-NoStartupMovies

Navigate to the following location:
...\Steam\steamapps\common\Borderlands 4\OakGame\Content\Movies

Look for and select the following files:

• 2KLOGO.bk2
  
• 010INT_MarcusIntro_71L.bk2
  
• 020RNR_RockAndRollIntro_71L.bk2
  
• GBXLOGO.bk2

Delete them.

These files will return if there's an update (probably), or if you reinstall the game.