Scala 3: wrongly accepted `modify` does nothing

Following code does not compile in Scala 2 and it should not compile in Scala 3. It is accepted instead, but the modify does nothing at all:

import com.softwaremill.quicklens._

object Main {
  case class Content(x: String)
  class A(val c: Content) {
    override def toString = s"x:${c.x}"
    def copy(x: String = c.x): A = new A(Content(x))
  }

  def main(args: Array[String]): Unit = {
    val a = new A(Content("A"))
    val am = a.modify(_.c).setTo(Content("B"))
    println(am)
  }
}

There is no copy accepting c parameter, therefore modify(_.c) is impossible to implement.

Result when running this in Scala 3 is:

x:A

The issue names no source files or tests; start by compiling the provided Main example under Scala 3 and comparing its behavior with Scala 2. Trace the modify(_.c) entry point and the copy-parameter handling. Done means Scala 3 rejects this case and a regression test covers it.