When you disconnect your bank or credit card account connected from online banking, it stays active. QuickBooks just stops downloading new transactions. You can always reconnect it to start downloading transactions again.
Since you can still see the tile for your bank and credit card accounts, let's refresh the connection of your browser's background processes. To start, access your QuickBooks Online (QBO) company using a private browser. Private mode prevents storing cache and cookies that might cause problems when running websites.
Here are the shortcut keys you can use:
Google Chrome: press Ctrl + Shift + N
Mozilla Firefox and Microsoft Edge: press Ctrl + Shift + P
Safari: press Command + Shift + N
Once signed in, check your Banking window again.
If this works, go back to your regular browser and clear the cache. This will remove the stored cache or cookies to refresh your browser. If the same thing happens, use another supported browser. It could be that the one you're currently using has a temporary issue with QuickBooks.