This (blank white screen) happens for me every time in Mullvad Browser (macOS), even with UBlock Origin disabled. It works fine in Orion and DuckDuckGo browsers.
Looking at the console, it's a WebGL error (perhaps because Mullvad disables it?):
Error: Failed to initialize WebGL
Uncaught (in promise) Error: Failed to initialize WebGL.
However, Google Maps, Apple Maps, even Mapbox's labs work fine in Mullvad Browser:
https://labs.mapbox.com/labs-standard/#16.2/48.860642/2.292287/-20/62
So perhaps something specific to Kagi's implementation?