So, you tried to open your inventory while sprinting.

What you've opened by pressing Shift + Tab is called the "Steam Overlay". It contains cool things like a clock, what your friends are doing, how long you've been playing for, and the guides (where I assume you've found this one from). It sure is helpful, but if you (like me) open the inventory while sprinting, it can get annoying.

And you can do this per-game, too, so it'll stay activated for your other games!

The process is simple:

1. Right click on Satisfactory in your library.

2. Select 'Properties'

3. Ensure the 'General' tab is open

4. Untick the box 'Enable Steam Overlay while in-game'

and that's it! Enjoy your inventory checking to the fullest extent!