Scala 3 Derivation fails on evidence parameters

[hearnadam]

The following code compiles and produces Right(Box(42)) on Scala 2:

import zio.json._

case class Box[A: Numeric](value: A)

implicit def decoder[A: Numeric: JsonDecoder] = DeriveJsonDecoder.gen[Box[A]]

"""{"value": 42}""".fromJson[Box[Int]]

    No given instance of type scala.deriving.Mirror.Of[Playground.Box[A]] was found for parameter mirror of method gen in object DeriveJsonDecoder. Failed to synthesize an instance of type scala.deriving.Mirror.Of[Playground.Box[A]]:
    	* class Box is not a generic product because it takes more than one parameter list
    	* class Box is not a generic sum because it is not a sealed class

https://scastie.scala-lang.org/Pg8k649ETC6cOq7ybPRRow

This seems to be a limitation of using mirrors for Scala 3.