How to Parse "MMMM D, YYYY"?

**Describe the bug**

I don't know what's going on, but when using dayjs in RSSHub, I get issues parsing MMMM D, YYYY.

```ts
import dayjs from 'dayjs';
import customParseFormat from 'dayjs/plugin/customParseFormat.js';
dayjs.extend(customParseFormat);

const dateString = "September 28, 2025";
const formatString = "MMMM D, YYYY";

const parsedDate = parseDate(dateString, formatString);
console.log(`test parsedDate: ${parsedDate}`); // Invalid Date
```

**Expected behavior**

I expect the code to parse the date properly.

**Information**
- Day.js Version 1.11.8
- OS: Windows
- Browser: Node
- Time zone: EDT

Start by running the supplied Node reproduction and then inspect the customParseFormat.js plugin entry point to trace how the shown format is handled. Done means the reported "September 28, 2025" input parses successfully with "MMMM D, YYYY" under the stated setup.

Written by the indexing model from the issue text.