Hello Lucas Peñaloza,
I wanted to follow up to see if you successfully completed the upgrade of the final node (PWGIRSQL1) and failing back your resources.
To summarize our last discussion regarding your final step:
The Risk: Update-ClusterFunctionalLevel is irreversible, but it is safe as long as all nodes are online, running the new OS, and you have passed the Test-Cluster validation.
The Strategy: There is no rush. You can leave the cluster in "Mixed Mode" for a few days to verify stability before running the command to lock in the new features.
If your cluster is now fully upgraded and stable, please consider accepting the answer as it helps other people sharing the same question benefit too. Thank you!
VP