Does this issue occur when all extensions are disabled?: Yes/No
Yes, but you need at least one language extension such as C# to get the Go To Definition function.

• VS Code Version: 1.96.4
• OS Version: Windows 10 build 19045

Steps to Reproduce:

1. Right click a class that is defined in a different file that is not already open, then click Go To Definition (or CTRL + click the class).

Expected:
File will open in a new window in normal mode

Actual:
File opens in preview mode and will be replaced the next time you use Go To Definition or open another file in preview mode.

Additional info:
The documentation states that Preview Mode is supposed to be used in two instances: when single clicking a file in the file explorer, or when opening it from the Quick Open if the workbench.editor.enablePreviewFromQuickOpen setting is set to true. It does not mention Go To Definition and there is no setting to control it.

Suggested fix:
Add a setting to control whether or not Go To Definition opens in preview mode.