This is an issue encountered while working with Font Awesome 6 Beta 2. The Font Awesome files can be found here: https://fontawesome.com/download

Font Awesome includes a custom divide implementation in _functions.scss. This implementation is then used to derive font sizes like this:

font-size: (divide($font-size, $fa-size-scale-base)) * 1em;

In scssphp this results in font-size: 1.5 * 1em; with the literal asterisk. In the dart-sass playground at https://www.sassmeister.com/ this will result in font-size: 1.5em.

If I remove the function call and replace it by a /, it works properly in both.

Simple reproducer:

@function divide($dividend, $divisor, $precision: 10) {
  @return $dividend / $divisor;
}

$fa-size-scale-base     : 16 !default;

.fa-xl {
    font-size: (divide(24, $fa-size-scale-base)) * 1em;
    font-size: ((24 / $fa-size-scale-base)) * 1em;
}

In the playground this will return:

.fa-xl {
  font-size: 1.5em;
  font-size: 1.5em;
}

In scssphp this will return:

.fa-xl {
  font-size: 1.5 * 1em;
  font-size: 1.5em;
}

I am using:

$ vendor/bin/pscss --version
1.8.1