This is true for both hosted and classic control planes. The error exists on both v1 and v2 but is more evident on v2.

How to reproduce:

• Start the ROSA wizard and proceed to the Cluster settings > Details section
• In the cluster name box, enter a single lowercase letter (this should be a valid name)
• Observe the error before leaving (blur) the box

Screenshots:

Version 1 (existing ROSA wizard)

Version 2 (future ROSA wizard)