File Name- Bumbli-graphics-shader-mcpe-1.20.mcpack ((link)) -

This indicates the shader is not compatible with your device's GPU (Graphics Processing Unit). Some shaders require specific renderdragon features. Try lowering your graphics settings or switching to a "lite" version of the shader.

The first step is to download the .mcpack file from a trusted source. Make sure you're downloading from a reputable website to avoid any potential malware. File name- Bumbli-Graphics-Shader-MCPE-1.20.mcpack