I found a minimal solution after reading the docs here https://rsyslog.readthedocs.io/en/latest/configuration/modules/imuxsock.html

  which is to create an rsyslog config file /etc/rsyslog.d/my-namespace.conf with the content:

input(type="imuxsock" Socket="/run/systemd/journal.my-namespace/syslog")

I found a minimal solution after reading the rsyslog docs which is to create an rsyslog config file /etc/rsyslog.d/my-namespace.conf with the content:

input(type="imuxsock" Socket="/run/systemd/journal.my-namespace/syslog")