https://github.com/mui-org/material-ui-pickers/blob/137019c0ca703bce44b2a66feebc34efe5e4cd41/lib/src/views/Calendar/Calendar.tsx#L181
Even with extending the utils for LocalizationProvider and writing custom getWeekdays does not help.
May be we need and renderWeekDays to override the default render of week day.
Locale = th

Locale = id

Yes that's definitely an issue. Originally it was done to support existed getWeekDays result.
Most helpful comment
Yes that's definitely an issue. Originally it was done to support existed
getWeekDaysresult.