All the new documents, be it text or otherwise, were automatically labeled for some reason. In the past they were always created as a blank, void of label or other markings, now they’re created with the label color which I most recently made, and this only happens to that one project alone.
Does this happen anywhere in the project, or only in one specific folder?
If it’s in one folder, check the Documents → Default Template for Subdocuments menu. (Note that you can set this option for Scrivener’s main folders, too, not just for the ones you create.)
If you open Project ▸ Project Settings... from the main menu, and select the Label pane, is this label you keep getting the default? It will be marked in bold if so, and you should see a button where you can select something else and then set a new default.
It is also possible to change the text itself of the original default, from “No Label”, but that won’t come with an associated colour, so that doesn’t quite sound like what you are seeing.