The bug
With 24w09a's changes to UI backgrounds and the replacement of the opaque dirt texture with a translucent texture everywhere, we can now see the world loading when we could not do so previously - the world would only render when just about finished loading, resulting in a seamless transition.
How to fix
Display the panorama up until the very end.
Linked issues
Attachments
Comments 2

Related to MC-262358
Can confirm.