Every time I start a world there is a high probability that all textures are bugged. Sometimes the textures of the menus are bugged before starting a world. This also happened before the Vibrant Visuals Update
I saw a splash potion rising and setting with the sun in the sky. I had command block textures underwater that were constantly changing to other textures instead of normal seaweed. The fire particles of candles have been changed to some sculk textures and most annoyingly the inventory and settings menu are completely bugged. Also the crosshair does not show up and is a translucent box.
This issue is being tracked at MCPE-202009.