unable to save file fields on the file create resource

Trying to post a file entity that have fields adds the file but fails to write field data on the file entity. For example, I have a file entity with an field called alt_text. When I post a file to the file resource create endpoint I get the file created but the field value fails to save.
Example post:

{
	"file": "somebase64data",
	"filename": "images.jpg",
	"field_file_image_alt_text": {
		"en": [{
			"value": "test",
		}]
	}
}

Patch attached.