Question about IBR plans after PAYE ends in 2028

I know that starting in July 1, 2028 there will only be two income driven repayment options; RAP and IBR. Looking at the conditions of IBR, it appears that the repayment period and monthly payment formula varies depending on when the borrowers loans were taken out: 1) 10% of discretionary income and 20 years maximum repayment period for borrowers after July 1, 2014, OR 2) 15% of discretionary income and 25 years maximum repayment period for borrowers before July 1, 2014.

If you have loans from both before and after July 1, 2014, which category do you fall into? I've seen it worded various ways in different online resources, so I'm a little confused.