RangeError from PlainYearMonth::toLocaleString

[kgram]

I cannot find any good explanation other than an error for this behaviour. It seems trying to get a localized string for a PlainMonthYear throws RangeError: Mismatching Calendars.

Temporal.PlainYearMonth.from('2024-11').toLocaleString('en')

The bundled code is minified and likely extremely optimized, so it is hard to say exactly what happens. The problem happens in toEpochMillis, where resolvedOptions is

{
  calendar: "gregory",
  locale: "en",
  month: "numeric",
  numberingSystem: "latn",
  timeZone: "UTC",
  year: "numeric"
}

and the slotsList is

[{
  branding: "PlainYearMonth",
  calendar: "iso8601",
  isoDay: 1,
  isoMonth: 11,
  isoYear: 2024,
}]

If I convert to a PlainDate first and only format the month/year (Temporal.PlainYearMonth.from('2024-11').toPlainDate({ day: 1 }).toLocaleString('en', { month: 'long', year: 'numeric' })), it works just fine. It appears that PlainYearMonth has strictCalendarChecks enabled in its ClassFormatConfig, so I'm guessing part of this is intentional, but it does not seem like there should be an error here.

I don't know if this is somehow related to my environment, but I don't understand what I could have done to affect any of this.