Go to your installation folder, default being -
C:\Program Files (x86)\Ubisoft\Ubisoft Game Launcher\games\Assassin's Creed Valhalla\videos
Rename or move these 3 files to a backup folder:
- ANVIL_Logo.webm
- PC_AMD_Ryzen.webm
- UbisoftLogo.webm
Then go to "en" folder, if your playing with English text language, "fr" for french etc. and do the same with those 3 files.
Enjoy