- Create new empty project
- Build it for iOS (with any backend Mono or IL2CPP)
- Run on a device
- See an error in the xCode log (full error in the attached file)

-------- Shader compilation failed
#version 100
#extension GL_EXT_frag_depth : enable
precision mediump float;
uniform highp vec4 _ProjectionParams;
uniform highp vec4 _ZBufferParams;
uniform highp mat4 unity_CameraToWorld;
....
-------- failed compiling:
fragment evaluation shader
WARNING: 0:4: extension 'GL_EXT_frag_depth' is not supported
ERROR: 0:31: Use of undeclared identifier 'gl_FragDepthEXT'