Hi @MartinU Hope you're doing well, it might be the reason for running the app installed, all you need to do just make sure to somehow pause that app for while then you can pause your store. furthermore, if still not works, then try to pause for the main admin account from the Shopify payments of your store occurred, somethings require authenticity from the main accounts. For further discussion, you can contact me via email email@example.com.
Try the procedures given below.
Log in as the store owner.
From your Shopify admin, click Settings, and then click Plan and permissions.
In the Store status section, click Pause and build.
If you agree with the terms, then click Pause and build.
Review the changes to your billing cycle, and then click Confirm changes.
Your store will be paused and running for a reduced subscription fee. If you want to start selling products again, then you can reopen your store at any time by choosing a new plan.