@custom-variant firefox (:-moz-any(&)); breaks in 4.3.3

[alexandre184]

What version of Tailwind CSS are you using?

v4.3.3

What build tool (or framework if it abstracts the build tool) are you using?

tailwindcss-rails v4.6.0

What version of Node.js are you using?

For example: v22.19.0

What browser are you using?

Firefox

What operating system are you using?

macOS

Reproduction URL

works in v3.4.19 : https://play.tailwindcss.com/9zUopjQm94?file=config

works in v4.3.2 : is there a way to get that version in the playground?

no longer works in v4.3.3 : https://play.tailwindcss.com/VNQvmXLHkC?file=css

Describe your issue

Maybe related to that change #20124. The css generated for firefox:bg-red-500 with the custom variant @custom-variant firefox (:-moz-any(&)); is in v4.3.3:

.firefox\:bg-red-500 :-moz-any(&) {
  background-color: var(--color-red-500);
}

It was in v4.3.2:

.firefox\:bg-red-500 {
  :-moz-any(&) {
    background-color: var(--color-red-500);
  }
}