Error when used inside :has()

[WebMechanic]

Hello,
love this plugin!! and I'm glad it still works in PostCSS 8.

With :has() gaining more browser support I tried using it, but the Plugin bails with an error:

Cannot read properties of undefined (reading 'apply')

/* change list layout mode */
ul:has( li:exactly(2) ) {
  display: grid;
  grid-auto-flow: column;
}

Please also consider a proper migration to PostCSS 8.