Hi, I hope you're doing great out there despite the issue that you're experiencing. I am an Independent advisor and I am here to help you in regards to your concern.

If you're already an Xbox Live Gold or Xbox Game Pass member, any days remaining in your subscription(s) will be converted to Xbox Game Pass Ultimate at a conversion ratio when you redeem the 24-month Xbox Game Pass Ultimate subscription, and those days will be added to your Xbox Game Pass Ultimate subscription up to a maximum of 36 months. Xbox Game Pass Ultimate subscriptions are limited to 36 months.

For your reference, you can check this link: https://support.xbox.com/en-US/help/subscriptio...

I would recommend ending the recurring payment first. :)