Documentation in chrony section for MC about Butane templating is showing a wrong .version key value in .bu example.
By looking at [0] I suppose this is a typo, and that should be 4.12.0.

https://coreos.github.io/butane/config-openshift-v4_12/

4.12.x

Have a look at 4.12 doc [0]

https://docs.openshift.com/container-platform/4.12/installing/install_config/installing-customizing.html#installation-special-config-chrony_installing-customizing

1. Have a look at the example for chrony .bu file
2. .version value is 4.11.0

.version in .bu file example is 4.11.0

Check against Butane docs whether this should be actually 4.12.0