Mapbox Expression using ["format", <TEXT>, {"text-color": "<COLOR>"}] causes toRenderColor error

[Dylansc22]

See demo video below of error which occurs in mapbox studio and on my live map app.

The cause of the bug
appears to be the text-filed attribute in mapbox studio, which makes use of the mapbox expression format

The expression 👇

[
  "case",
  [
    "all",
    ["has", "name"],
    ["has", "name_en"],
    [
      "!=",
      ["get", "name"],
      ["get", "name_en"]
    ]
  ],
  [
    "format",
    ["get", "name_en"],
    {
      "font-scale": 1
    },
    "\n",
    ["get", "name"],
    {
      "font-scale": 0.8,
     "text-color": "grey"
    }
  ],
  ["format", ["get", "name"]]
]

The error it causes 👇

Uncaught TypeError: r.toRenderColor is not a function
    at o_._setPaintValue (147.ddd73483.js:8:36290)
    at o_.updatePaintArray (147.ddd73483.js:8:36196)
    at 147.ddd73483.js:8:41263

If I remove the "text-color": "grey" condition from the format statement, the error does not occur.

Screen.Recording.2024-12-02.at.10.28.41.PM.3.mov