`RuleExit` doesn't work for custom at-rules

This pretty much summarizes it:

@global {
  h1 {
    color: red;
  }
}

let inGlobal = 0;


lightningcss.transform({
  code: Buffer.from(content),
  filename: ctx.ns,
  minify: true,
  targets: lightningcss.browserslistToTargets(browserslist(ctx.opts.browserslist || 'defaults')),
  drafts: {
    nesting: true,
    customMedia: true,
  },
  customAtRules: {
    global: {
      body: 'rule-list',
    },
  },
  visitor: {
    Rule: {
      custom: {
        global() {
          inGlobal += 1;
        },
      },
    },
    RuleExit: {
      custom: {
        global() {
          inGlobal -= 1;
        },
      },
    },
  },
});

console.log(inGlobal); // 1

Start with the lightningcss.transform visitor API shown in the report, especially the Rule and RuleExit handlers for custom at-rules and the customAtRules global configuration. Reproduce the example and trace why RuleExit does not run for the custom rule; done means the displayed input balances the callbacks and produces inGlobal as 0.