Normally when i'm in the middle of coding or looking busy my keyboard layout will randomly change. Meaning that declaring string variables becomes a right pain as the @ symbol and " quotes change places (UK QWERTY layout).

Apparently, this is done by a keyboard shortcut that switches between input languages. This is Left Alt + Shift which I tend to press quite a lot for a few VS code shortcuts like formatting a document (alt + shift + f). Commonly leaving off the F because I have fat fingers.

You can always remap this shortcut in the modern settings app:

Open Settings > Time & Language

Under Related settings > Spelling, typing & keyboard settings

Under More keyboard settings > Advanced keyboard settings > Language bar options > Advanced Key Settings

Press the Change Key Sequence to map a new shortcut