Where are Lightroom Classic color label settings stored?

Color labels are stored in the catalog as text, and which text defines which color is stored in the color label set. By default the text is simply the label color, so a red label is stored as the word 'Red'. You can change that yourself, however, by creating a different label set. In that case a red label could be defined by any other word, such as 'HDR' or 'To be worked on'. What often happens when people move a catalog to a different computer is that these custom label sets are reset to the default, so once again Lightroom is looking for the word 'Red' to show a red label, but it finds the word 'HDR' and does not know what color that is supposed to be. So what you need to do is either copy the label sets template file to the new computer and then reselect your custom set, or recreate the custom label set. https://havecamerawilltravel.com/lightroom/lightroom-customize-color-labels/