the “Super Secret Settings” thing is VANILLA MINECRAFT, and good luck turning it off without restarting Minecraft, because you have to cycle through everything until you arrive at what you BELIEVE is normal, and then turns out that was not the normal so you have to cycle further.
If any shader is enabled, a new line appears in the Debug screen (which is enabled by pressing F3) that starts with “shader:” and shows which shader is currently enabled. To return to normal mode, you need to switch shaders until this line disappears.