let is redundant when the lambda parameter is only used as a qualifier in a call expression.

If you need to give a name to the qualifying expression, declare a local variable.

Example:

  fun splitNumbers() {
      "1,2,3".let { it.split(',') }
  }

A quick-fix removes the extra let() call:

  fun example() {
      "1,2,3".split(',')
  }

Alternative:

  fun splitNumbers() {
      val numbers = "1,2,3"
      numbers.split(',')
  }