another thread said this may be the plex healthcheck that docker is running all the time. You can disable the healthcheck in advanced settings for plex container, or userscript schedule deletion of the health logs hourly/daily. Would prefer for the log to work without this workaround but this does seem to work for now...
find /run/docker/containerd/daemon/io.containerd.runtime.v2.task/moby/ -maxdepth 999999 -noleaf -type f -name "log.json" -exec rm -v "{}" \;