The behavior you're describing in Visual Studio Code (VSCode) happens when "Overwrite mode" is enabled. In this mode, typing overwrites the text ahead instead of inserting new text. This is similar to the "Insert/Overwrite" mode in many text editors.

Check if Overwrite Mode is Enabled

• Look at the status bar at the bottom of VSCode. If you see "OVR" (overwrite), it means overwrite mode is active.
• If you see "INS" (insert), overwrite mode is not active, and something else may be causing the issue.