During the built of our container images, we copy the RPM files into the container image and install them locally. This has the side effect the RPM files are added as a layer with the copy command and can't be removed. This bloats the container image additional with 645 MB (compressed) with the size of the RPMs in the /tmp folder.
A solution to solve this problem is installing the RPMs not from the local filesystem and install them instead from an URL.
The problematic part is this line here:
When installing from a remote URL the RPMs are not added as a layer in the image.