I did a search for you and found out the below information:
The warning message is due to a product upgrade in Decision Data rule. During the opening of the Decision Data rule, prpc detects that there is a need to upgrade the original Decision Data rule (created on 7.13) to align with the new platform (7.31), thus an automatic upgrading is happening in the background. This is for the sake of forward compatibility. However since the upgrading process changes the Decision Data rule, a warning is generated to inform the user what has happened, and what is suggested to do next.
[Recommended] If the user save or save-as the original rule, the warning message will go away next time the new rule is opened.
If the user ignores the warning and does nothing, all fine as well. The backward compatibility is also maintained. There might be a small performance impact because the automatic background upgrading will happen whenever this rule is used in the application.