Have you ever typed fast on a keyboard? Then there was a sound along with a notification screen.
Sticky Keys is an accessibility feature in Windows that allows users to press modifier keys such as Shift, Ctrl, or Alt one at a time, instead of holding them down. This is especially useful for people who have trouble pressing multiple keys at once.
The fact that Sticky Keys works when Shift is pressed repeatedly is because Windows is set to notify you when the Shift key is pressed more than 5 times in a row. You can turn this setting off. If you don't want Sticky Keys to be accidentally activated
How to turn off Sticky Keys: (For Windows 11)
1. Open Settings: Right-click the Start button and select "Settings".
2. Go to Accessibility: Select "Keyboard"
3. In the Sticky, Filter and Toggle: section, open the Notification settings section.
4. You will find Notify me when … and Play sound when …, check both boxes and that's it, there will be no more messages and noise bothering you.
NOTE: These steps may vary slightly. It depends on the version of Windows you're using.