util 12.2 UMD is treated accidentally as ESM

The following code produces the following error:
```html

```

`Uncaught ReferenceError: exports is not defined: [utils.12.2.js:1:728](file:///C:/Users/akira/src/test/utils.12.2.js)`

I can only use UMD since my Firefox extension MV2 can only use that. 12.1 index.js seems to load fine but 12.2 doesn't. Is this because of #627 ?