I finally got it working with further logic tweaking. Thank you so much to everyone.
function showHideSection(executionContext)
{
var formContext = executionContext.getFormContext();
var createdOn = formContext.getAttribute("createdon").getValue();
var OldRateDate = new Date("2022-12-01");
if (createdOn == null || createdOn > OldRateDate)
{
formContext.ui.tabs.get("{226d192b-e5b7-45f4-886a-76f1fd1a2ec2}").sections.get("reimbursement_rate_125").setVisible(true);
formContext.ui.tabs.get("{226d192b-e5b7-45f4-886a-76f1fd1a2ec2}").sections.get("reimbursement_clause_old").setVisible(false);
}
else
{
formContext.ui.tabs.get("{226d192b-e5b7-45f4-886a-76f1fd1a2ec2}").sections.get("reimbursement_rate_125").setVisible(false);
formContext.ui.tabs.get("{226d192b-e5b7-45f4-886a-76f1fd1a2ec2}").sections.get("reimbursement_clause_old").setVisible(true);
}
}