That’s an unfortunate side effect of the Developers deciding to only have 5 toolbar icon options, instead of 6. Other than not wanting to support so many alternatives, since they already had the icon set for the large colored icons, I am not sure why they decided to remove the large-standard icons.
You might want to go put in your 2c on issue #9913, which asks for a set of large standard icons to be added back in. The more “regular users” who weigh in, the more likely it is that the Developers team will consider implementing the request. Good luck.