Uninformative error message for ambiguous implicit conversions

[Alex1005a]

Reproduction steps

Scala version: 2.13.18

trait Ops {
  implicit class OpsSyntax[P](private val p: P) {
    def add[P1](p: P): P = ???
  }
}
object Foo extends Ops {
  final case class Bar()
  object Bar extends Ops {
    def x(): Bar = ???
  }
}

object TestErrMsg {
  def test(c: Foo.Bar) = {
    Foo.Bar.x().add(c)
  }
}

Problem

The compiler reports the error message: value add is not a member of testbaderrormessage.this.Foo.Bar. If the type parameter P1 is removed from add, a more informative error message is reported, describing which implicit conversions lead to ambiguity.

[SethTisue]

Scala 3.8.4-RC2:

-- [E007] Type Mismatch Error: -------------------------------------------------
15 |    Foo.Bar.x().add(c)
   |    ^^^^^^^^^^^
   |Found:    Foo.Bar
   |Required: ?{ add: ? }
   |Note that implicit extension methods cannot be applied because they are ambiguous;
   |both Foo.OpsSyntax and Foo.Bar.OpsSyntax provide an extension method `add` on Foo.Bar
   |
   | longer explanation available when compiling with `-explain`

[som-snytt]

The helpful message:

error: type mismatch;
 found   : Foo.Bar
 required: ?{def add(x$1: ? >: Foo.Bar): ?}
Note that implicit conversions are not applicable because they are ambiguous:
 both method OpsSyntax in trait Ops of type [P](p: P): Foo.OpsSyntax[P]
 and method OpsSyntax in trait Ops of type [P](p: P): Foo.Bar.OpsSyntax[P]
 are possible conversion functions from Foo.Bar to ?{def add(x$1: ? >: Foo.Bar): ?}
    Foo.Bar.x().add(c)
             ^
error: value add is not a member of Foo.Bar
    Foo.Bar.x().add(c)
                ^

I approve Scala 2's use of colon after "ambiguous".