Hi Evelyne, thanks for joining us on the Community
We're not aware of any widespread issues with Revolut banking in QuickBooks at the moment. For troubleshooting purposes, please try re-authorising the account by signing into QB through a different web browser or incognito window.
Any transactions that have already been added or matched in QuickBooks will remain, even if the connection becomes expired or disconnected, so you won't need to worry about starting over. :)