Can’t change the region of my Apple Store

Hello!

That is correct. If you have an active subscription, you will not be able to change the country in iTune or Apple ID.

Change your Apple ID country or region

What to do before changing your country or region

1. Spend any store credit remaining on your Apple ID. You must also wait for any pending store credit refunds to process before you can change your country or region. Learn what to do if your remaining store credit is less than the cost of a single item.
2. Cancel any subscriptions, including Apple Music, and wait until the end of the subscription period to change your country or region. You'll also have to wait for any memberships, pre-orders, movie rentals, or Season Passes to complete.
3. Have a payment method for your new country or region on hand. For example, German credit cards can be used to buy content only from the German App Store, iTunes Store, or Apple Books.
4. Back up your iPhone, iPad, or iPod touch to iTunes. You might need to temporarily downgrade your iCloud storage until you switch to the new country or region. You won't lose any iCloud data in the process. After you change your account to a new country or region, re-enroll in a new storage plan to continue using iCloud storage.

If needed, you can ask the iTunes Store staff to expire subscriptions immediately, and zero any balance. That might speed things up a few weeks. iTunes Store - Contact Us - Official Apple Support