An identifier inside a string should be colored as identifier, not as string.
Probably it's related to the execution order applying the colors. Now the string scheme has more importance than identifier, and it should be the opposite. An example:
`"Here is a $variable is inside a string"`
The ideal in this case I believe is firstly applying the string color, and then, applying the identifier color which would let the identifier with a different color even it is inside the string, the point is to call the attention to it. In my editor, it is using the string color, ignoring the identifier color. Outside a string the identifier color is OK, but when inside a string, the priority color used is the string color, not identifier's color.