half4 type variables are cased to float4 when shaders are compiled on Metal or GLES graphics API

Reproduction steps:
1. Open the attached “BugRepro“
2. In the Project window, select the “Assets/Shader/TestShader” shader
3. In the inspector, in the “Compile and show code” popup menu, select the Metal graphics API
4. Click “Compile and show code”
5. In the opened code, observe the “u_xlat16_0” and “_TintColor” variables type and their usage

Expected result: the variable type stays the same as the declared type when they are used
Actual result: the variables are cast to float4 when they are used

Reproducible with: 2021.3.34f1, 2022.3.17f1, 2023.2.6f1, 2023.3.0b3

Reproducible on: Windows 11
Not reproducible on: No other environments tested

Note: On the Editor version 2023.3.0b3, in the compilied code the “_TintColor” variable is declared as a float4