Welcome to the thread, @blytcs. Let me share some information about why the System Administration shows in the Audit Log.

The system administrator in QuickBooks Online is responsible for managing and administering your account. If you see a post that System Administration do some changes, this can happen for several reasons, such as:

• You change a record, and the change affects another record. For example, if you edit a payment and link it to a different invoice, you may see a System Administration event for a change to the original invoice.
• You connect a third-party app to QuickBooks. When the third-party app sends data to QuickBooks, or when it makes a change to your existing data, this appears as a System Administration event.
• You create a recurring transaction, such as a recurring expense. When QuickBooks automatically adds an instance of the transaction to your books, a System Administration event appears in the audit log.
• You set up other events to happen automatically, even when you’re not signed in. For example, a System Administration event may appear when there's an update to your bank feeds.

To learn more about what the audit log can do and how to use it to keep an audit trail, see this article: Use the audit log in QuickBooks Online. It also includes a detailed explanation about other special users such as online banking and import administration and support representatives.

Let me know if you have follow-up questions about System administration user in QuickBooks Online. I'm just around to help. Take care always.