Docker image created by MatLab has an OS (ubuntu) version different than the host

Question

I have a docker image of a standalone app created by MatLab using the compiler.package.docker function. My issue is that I'm using a shared library which is needed by a function inside the code in the image, but I get the error that the GLIBC version is 2.27 while my library needs at least 2.28.
When I checked the ubuntu version running in the image, I found that it's Ubuntu 18.04.6 (bionic beaver) but my host machine (the one I had MatLab run on and create the docker image on) is Ubuntu 20.04.4 (focal fossa), so why does my docker image has a different version of Ubuntu running? and is there a way to upgrade this version to ubuntu 20.04.4 either through MatLab or by executing a specific command inside the running image?

Also, note that I can't build the docker image outside MatLab because MatLab adds its own dependencies which are needed to run the standalone app.