EDIT: Uninstall the extension, there are many other far better maintained formatters out there (e.g. Beautify)
OK, check if you have installed this extension: “JS-CSS-HTML formatter”.
Now if you have, press CTRL+SHIFT+P, type “Formatter” and you should see an option that says Formatter Config.
After selecting that option, a file named formatter.json opens and all you do is edit the property (named onSave) from having true to being false.
Restart vs code and voilà!! It stopped auto formatting. (yay!!!!)