Mounting a file into a folder will not change the permission of the folder it was mounted in.
By any chance is the jobs folder itself configured as a volume? If so, the host folder will be bind mounted into the container folder and as such eclipsing the existing container folder. As a result the original permissions of the container folder become replaced by the permissions of the mounted folder.
You might want to share your complete compose file, so we see the full picture. And ls -l outputs of everything relevant.