AppImage created on Ubuntu 18.04 and does not work in 20.04 because of `GLIBC_2.30' not found error

Created AppImage with `appimagetool` under Ubuntu 18.04 or Ubuntu 18.04 docker image, however it works in Ubuntu 18.04 and does not work in 20.04 because of following error:

```
> ./MyApp.docker.AppImage
mkdir: /tmp/appimage_extracted_246844dbdeeca1f1fe512ed8c7848908/Qt/libs/libc.so.6:
version `GLIBC_2.30' not found (required by /lib/x86_64-linux-gnu/libselinux.so.1)
*** stack smashing detected ***: terminated
Aborted (core dumped)
```

Any ideas how to solve this? This happened even if I bundle glibs a well. Use higher level tool? `linuxdeploy` does now work for me as well as it tries to bundle system Qt libraries but need to bundle custom built Qt version (more modern) than installed in the system and does not create AppImage at all.