False positive "Unused CSS selector" on ":global() + .class"

[nikolay-makhonin-playhub]

Describe the bug

Svelte incorrectly marks :global() + .class selector as unused and removes it.

Reproduction

REPL: https://svelte.dev/playground/f6023640ca8e4b659c6bbae9966dca97?version=5.23.0

<!-- Toggle.svelte -->
<input type="checkbox" id="checkbox">
<slot />

<!-- App.svelte -->
<script>
  import Toggle from './Toggle.svelte'
</script>

<div>
  <!-- Uncomment this and the selector works -->
  <!-- <span></span> -->
  <Toggle />
  <label for="checkbox" class="btn">Button</label>
</div>

<style>
  .btn {
    background-color: blue;
    color: white;
  }
  
  :global(:checked) + .btn {
    background-color: red;
    color: black;
  }
</style>

The :global(:checked) + .btn selector doesn't work because Svelte removes it as "unused".

Adding an empty <span></span> before the target element makes it work:

<div>
  <span></span>
  <Toggle />
  <label for="checkbox" class="btn">Button</label>
</div>

Logs

System Info

Svelte Repl 5.23.0

Severity

annoyance