Microsoft change the default behavior of print screen button on Windows 11.
When PrtSC KEY button pressed it opens "Snipping Tool" instead of instant screengrab.

Instead of just pressing the PrtSC KEY you can use the following:
- Windows KEY + PrtSC KEY
- Alt KEY + PrtSC KEY

How to change Print Screen key behavior:
Go to Settings > Accessibility > Keyboard and toggle "Use the Print screen key to open Snipping Tool." 

1. Press Windows KEY and Type: Settings
2. Select the "Accessibility" category on the Left
3. Select the "Keyboard" setting
4. Find the "Use the Print screen key to open Snipping Tool" and Toggle the setting on or off