Gamepass Ultimate and Gold Conversion

So, I was going to add 12 months of xbox live gold onto my account because my gamepass ultimate subscription was about to run out and I just wanted to go back to the standard gold subscription. I got a prompt about converting the 12 months of gold to 4
of gamepass and wanted more clarity. Does this mean just 4 months of gamepass ultimate, or is it 4 months of gamepass and the remaining 8 months leave you with gold?

:)