Running Obsidian 1.3.7 on Windows 10. All plugins disabled.
Seemingly randomly, after starting Obsidian, left-clicking a file in the File Explorer causes the document to open in a new tab group. Every document I click opens in a new tab group. Once the document is opened, any link I click within it also opens in a new tab group of its own containing only that document.
The issue can be worked around by restarting Obsidian, but reoccurs a few days later.
Note that I am not pressing any additional keys when this occurs, nor am I right-clicking or selecting anything from a context menu. Finally, I have not customized any shortcuts.