glxinfo shows different versions in the same machine on different runs

Question

I am trying to get my OpenGL version. Most of the time, I am shown OpenGL Core Profile is 3.3 but sometimes it shows 4.3. Any idea why it would happen? Also, how to fix permanently to 4.3?

soham@soham-machine:~$ glxinfo | grep version
server glx version string: 1.4
client glx version string: 1.4
GLX version: 1.4
    Max core profile version: 4.3
    Max compat profile version: 3.0
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.1
OpenGL core profile version string: 4.3 (Core Profile) Mesa 18.0.5
OpenGL core profile shading language version string: 4.30
OpenGL version string: 3.0 Mesa 18.0.5
OpenGL shading language version string: 1.30
OpenGL ES profile version string: OpenGL ES 3.1 Mesa 18.0.5
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.10

soham@soham-machine:~$ glxinfo | grep version
server glx version string: 1.4
client glx version string: 1.4
GLX version: 1.4
    Max core profile version: 3.3
    Max compat profile version: 3.0
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.1
OpenGL core profile version string: 3.3 (Core Profile) Mesa 18.0.5
OpenGL core profile shading language version string: 3.30
OpenGL version string: 3.0 Mesa 18.0.5
OpenGL shading language version string: 1.30
OpenGL ES profile version string: OpenGL ES 3.0 Mesa 18.0.5
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00

My machine is the following:

Distributor ID: Ubuntu
Description:    Ubuntu 16.04.7 LTS
Release:    16.04
Codename:   xenial

The Graphics is Intel integrated graphics:

OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) Haswell Mobile

Answer 1

I had to update my kernel version to 4.15 to fix the problem:

sudo apt-get install --install-recommends linux-generic-hwe-16.04

After this, I restarted the system, now I have OpenGL 4.5:

server glx version string: 1.4
client glx version string: 1.4
GLX version: 1.4
    Max core profile version: 4.5
    Max compat profile version: 3.0
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.1
OpenGL core profile version string: 4.5 (Core Profile) Mesa 18.0.5
OpenGL core profile shading language version string: 4.50
OpenGL version string: 3.0 Mesa 18.0.5
OpenGL shading language version string: 1.30
OpenGL ES profile version string: OpenGL ES 3.1 Mesa 18.0.5
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.10