Extension methods ambiguous despite being the same

[rjolly]

Compiler version

3.8.0-RC1-bin-20251002-b7cae74-NIGHTLY

Minimized code

trait R[T]:
  extension (x: T) def m: T

trait S[T] extends R[T]

trait A[T]:
  given R[T] = scala.compiletime.deferred

class B[T : S](x: T) extends A[T]:
  override given S[T] = summon
  x.m

Output

  x.m
  ^
Found:    (B.this.x : T)
Required: ?{ m: ? }
Note that implicit extension methods cannot be applied because they are ambiguous;
both given instance evidence$1 in class B and given instance given_S_T in class B provide an extension method `m` on (B.this.x : T)

Expectation

Should not be ambiguous since the typeclass instance is the same.