I don't know if it goes back to that older version though

Restarting the rke2-server-agent should also rotate them.

I had something similar happen recently and ultimately I had to get the cluster token from a secret and rejoin the nodes

It was basically:

kubectl get <http://clusterregistrationtokens.management.cattle.io/default-token|clusterregistrationtokens.management.cattle.io/default-token> -n <REPLACE WITH YOUR CLUSTER ID> -o yaml

for the token. Then I had to run

systemctl stop rancher-system-agent.service && ln -s /opt/rke2/bin/rke2 /usr/local/bin/rke2 && curl -fL <https://rancher.example.edu/system-agent-install.sh> | sudo sh -s - --server <https://rancher.example.edu>    --label '<http://cattle.io/os=linux|cattle.io/os=linux>' --token <token> --no-roles

On all of the nodes.