SUMMARY
3D graph plots in KAlgebra Mobile are not rendered.

STEPS TO REPRODUCE
1. Install kalgebra on the PinePhone. I am using Manjaro ARM Plasma Mobile.
2. Run KAlgebra Mobile from the menu.
3. Go to Graph 3D.
4. Touch the circled + button to open the popup.
5. Touch the + button in the popup to add the example sin x*sin y plot. You can also try any other function. It does not make a difference.

OBSERVED RESULT
The plot area remains completely black.

EXPECTED RESULT
The 3D graph is rendered.

SOFTWARE/OS VERSIONS
Manjaro ARM Plasma Mobile
Pine64 PinePhone (1.2) (Allwinner A64 / Cortex A53 aarch64)
KDE Plasma Version: 5.25.5
KDE Frameworks Version: 5.98.0
Qt Version: 5.15.6
kalgebra 22.08.1-1 (Manjaro ARM Package)

ADDITIONAL INFORMATION
This is the terminal output. I believe the first error to be the root cause and the remaining ones to be followups that ultimately lead to nothing at all being rendered:

QOpenGLShader::compile(Fragment): 0:4(2): error: No precision specified in this scope for type `float'

*** Problematic Fragment shader source code ***
#ifdef GL_KHR_blend_equation_advanced
#extension GL_ARB_fragment_coord_conventions : enable
#extension GL_KHR_blend_equation_advanced : enable
#endif
#ifndef GL_FRAGMENT_PRECISION_HIGH
#define highp mediump
#endif
#line 1
uniform mediump vec4 color;
void main(void)
{
   float w = 10.*gl_FragCoord.w;
   highp vec4 zvec = vec4(w, w, w, 1.0);   gl_FragColor = mix(color, zvec, vec4(.5,.5,.5,1.));
}
***
QOpenGLShader::link: error: program lacks a fragment shader

QOpenGLShader::link: error: program lacks a fragment shader

QOpenGLShaderProgram::uniformLocation(matrix): shader program is not linked
QOpenGLShaderProgram::attributeLocation(vertex): shader program is not linked
QOpenGLShaderProgram::attributeLocation(normal): shader program is not linked
QOpenGLShaderProgram::attributeLocation(vertex): shader program is not linked
QOpenGLShaderProgram::uniformLocation(color): shader program is not linked
QOpenGLShaderProgram::uniformLocation(color): shader program is not linked
QOpenGLShaderProgram::uniformLocation(color): shader program is not linked
QOpenGLShaderProgram::attributeLocation(vertex): shader program is not linked
QOpenGLShaderProgram::uniformLocation(color): shader program is not linked
QOpenGLShader::link: error: program lacks a fragment shader

QOpenGLShaderProgram::uniformLocation(matrix): shader program is not linked
QOpenGLShaderProgram::attributeLocation(vertex): shader program is not linked
QOpenGLShaderProgram::attributeLocation(normal): shader program is not linked
QOpenGLShaderProgram::attributeLocation(vertex): shader program is not linked
QOpenGLShaderProgram::uniformLocation(color): shader program is not linked
QOpenGLShaderProgram::uniformLocation(color): shader program is not linked
QOpenGLShaderProgram::uniformLocation(color): shader program is not linked
QOpenGLShaderProgram::attributeLocation(vertex): shader program is not linked
QOpenGLShaderProgram::uniformLocation(color): shader program is not linked