Well, I suspect your python repo's python is to blame. The assert happens inside Python. Is there anything interesting printed on the commandline? I've seen something like this on macOS when Krita tries to load a different Python from the one it's built with.

ok. let me downgrade python...

downgrading and using system default version of python does not help

here is the console output:
___

-kpxb:~> krita
Setting XDG_DATA_DIRS "/usr/bin/../share:/home/aram/.local/share/flatpak/exports/share:/var/lib/flatpak/exports/share:/usr/local/share:/usr/share:/var/lib/snapd/desktop"
Override language: ""
OpenGL Info 
  Vendor:  Intel Open Source Technology Center 
  Renderer:  "Mesa DRI Intel(R) Sandybridge Mobile " 
  Version:  "3.0 Mesa 17.0.5" 
  Shading language:  1.30 
  Requested format:  QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize -1, greenBufferSize -1, blueBufferSize -1, alphaBufferSize -1, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::SwapBehavior(DoubleBuffer), swapInterval 0, colorSpace QSurfaceFormat::ColorSpace(DefaultColorSpace), profile  QSurfaceFormat::OpenGLContextProfile(CompatibilityProfile)) 
  Current format:    QSurfaceFormat(version 3.0, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 24, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 0, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::SwapBehavior(DoubleBuffer), swapInterval 0, colorSpace QSurfaceFormat::ColorSpace(DefaultColorSpace), profile  QSurfaceFormat::OpenGLContextProfile(NoProfile)) 
     Version: 3.0
     Supports deprecated functions true 
     is OpenGL ES: false 
krita has opengl true
Available translations QSet("he", "fa", "en_US", "ug", "hi", "lt", "da", "lv", "uk", "fi", "de", "sk", "hr", "sl", "be", "hu", "bg", "fr", "sq", "en_GB", "sv", "mk", "ia", "nds", "ga", "kk", "ta", "mr", "km", "ko", "vi", "zh_CN", "zh_TW", "mai", "th", "ca", "gl", "pa", "is", "it", "el", "nb", "tr", "eo", "ne", "ro", "pl", "es", "et", "eu", "ja", "ru", "nl", "wa", "cs", "nn", "pt_BR", "pt", "ast", "ar", "ca@valencia")
Available domain translations QSet("he", "fa", "en_US", "ug", "hi", "lt", "da", "lv", "uk", "fi", "de", "sk", "hr", "sl", "be", "hu", "bg", "fr", "sq", "en_GB", "sv", "mk", "ia", "nds", "ga", "kk", "ta", "mr", "km", "ko", "vi", "zh_CN", "zh_TW", "mai", "th", "ca", "gl", "pa", "is", "it", "el", "nb", "tr", "eo", "ne", "ro", "pl", "es", "et", "eu", "ja", "ru", "nl", "wa", "cs", "nn", "pt_BR", "pt", "ast", "ar", "ca@valencia")
Qt UI languages ("en-US", "en-GB") "en_US.UTF-8"
Icon theme "ubuntu-mono-dark" not found.
input profiles were read from ' /usr/share/krita/input '.
Loading Python plugin
"/usr/lib64/libpython3.4m.so.1.0" true
Creating s_pythonLibrary /usr/lib64/libpython3.4m.so
Found krita-python-libs at "/usr/lib64/krita-python-libs"
Setting python paths: "/home/aram/.local/share/krita/:/usr/share/krita/:/home/aram/.local/share/krita/pykrita/:/usr/share/krita/pykrita/:/usr/share/pykrita/:/usr/lib64/krita-python-libs"
KCrash: Application 'krita' crashing...
KCrash: Attempting to start /usr/lib64/libexec/drkonqi from kdeinit
sock_file=/run/user/1000/kdeinit5__0

[1]+  Stopped                 krita

No, that doesn't help much. I doesn't print the fatal error Python apparently encounters. Are you sure that after downgrading python, you're getting the same backtrace? And does the appimage work?

Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information as soon as possible and set the bug status as REPORTED. Due to regular bug tracker maintenance, if the bug is still in NEEDSINFO status with no change in 30 days, the bug will be closed as RESOLVED > WORKSFORME due to lack of needed information.

For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

If you have already provided the requested information, please set the bug status as REPORTED so that the KDE team knows that the bug is ready to be confirmed.

Thank you for helping us make KDE software even better for everyone!

Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least 30 days. The bug is now closed as RESOLVED > WORKSFORME due to lack of needed information.

For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

Thank you for helping us make KDE software even better for everyone!