Welcome to the Community, @anri.

There are times that the browser is full of frequently accessed page resources, causing some unusual responses. To isolate this, try logging into your QuickBooks Online (QBO) account using a private browser (incognito).

Here's how:

• Press Ctrl + Shift + N (Google Chrome).
• Ctrl + Shift + P (Firefox).
• Control + Option + P (Safari).

Once signed in, try to resubscribe again using the updated billing to credit card details.

If it's successful, go back to your default browser and perform a clear cache. Every so often the cache becomes overwhelmed with older data which can potentially cause viewing and performance issues. Clearing it will refresh the system, and you'll be able to work with a clean slate. However, if the issue persists, try using other supported browsers.

Reach out to me in the comment section below if you have any other issues or concerns. I'm always here to help. Have a wonderful day!