Thanks for replying back here and providing us with the information we need so we can further assist you and provide an accurate answer, @kimi21.
As I've assessed the screenshot you've provided, the error is a known issue for QuickBooks Desktop only. It is an error that occurs when trying to access or sync a third-party application. Since you're using QuickBooks Online, you can disregard the error message and I'd suggest not opening the link for safety purposes.
Furthermore, once you have installed applications, you have the option to disconnect an app or perform this action on behalf of one of your clients. Moreover, if you need to cancel or modify your subscription, you can easily do so through the Intuit App Center. For further information on this topic, please feel free to refer to the following article: Disconnect an app and change subscription.
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