Hello, the Asia/Calcutta time zone has been deemed obsolete. It has been replaced by Asia/Kolkatat.
If you want to disable this timezone in select you should rebuild cattr with some edits in app/core/components/TimezonePicker.vue file. You should add this string if (timezoneName === 'Asia/Calcutta') return on 108 line. Like this
moment.tz.names().map(timezoneName => {
if (this.timezones.some(t => t.value === timezoneName)) {
return;
}
if (timezoneName === 'Asia/Calcutta') return
if (typeof timezoneName !== 'string') return;
this.timezones.push({
value: timezoneName,
label: this.formatTimezone(timezoneName),
});
});