VisualStudio highlights all my code green, I don't know how to disable this effect/feature

I was writing the code normally and then I fear I have accidentally pressed some shortcut that made my code all highlighted green, I tried to press some combos but nothing changed, I deleted the script from Unity and pasted the code into a new script, and it gave me the same issue. If I press anywhere it doesn't change anything and it only disappears for a moment when I edit the code and then it goes back to being green. I imagine this feature has a purpose that I'm not understanding but at the moment it's not doing anything for me except making the code less readable. Does anyone know what caused this effect, how can I remove it, and what is it's purpose? Thanks for your help.