Change machine from a Jenkins node to fail the ssh connection

We have a node on the Jenkins master (actually, multiple nodes) that connects with the help of the SSH key verification strategy and manual trust. We correctly connect the slave to Jenkins in this way (a Sierra Mac machine to be specific)
Now the Sierra is old, we have to use HighSierra. We are not just upgrading the machine, we are completely erasing it, installing HighSierra from scratch, installing everything we need on this slave and connecting it with the same jenkins node (no modification n & # 39, was again brought on Jenkins)
We have an error when Jenkins tries to connect to the node:

WARNING: The SSH key for this host is not approved at this time.
Connections will be refused until this new key is authorized.

We try to solve the SSH problem by connecting to master and ssh-keygen -R with this whole node, then connecting via ssh to the node and everything works fine … But Jenkins still can not connect with the same message.

Now, it's fun, we create a new node that is a copy of the first one and we just save it. No modification. It connects instantly.

So, I guess it's somewhere in Jenkins where it stores the fingerprint (which changes after the reinstallation) but I could not find where.

For now, the workaround of removing the node and creating one after reinstallation works fine, but I wonder if there is another way to do it.

Something to say Jenkins to forget about the fingerprint?

Maybe the problem is elsewhere?

We use Jenkins 2.32.3 and our SSH Slaves plugin is v1.15

Thank you for your enlightenment