I can't see this option in 2020.2.6 anymore.
2020.2.5
2020.2.6
We have attempted to confirm your findings comparing 2020.2.5 to 2020.2.6 but our results differ from yours above. The "Dynamic IP.." checkbox only appears when selecting nodes where this setting is enabled. Hence, it can only be used to disable Dynamic IPs, not enable existing nodes in bulk to use a dynamic IP address.