dayjs.tz instances produce inconsistent results with repeated calls

When calling dayjs.tz(...) multiple times on the same date, the timezone may shift unexpectedly.

const dt = dayjs('2020-08-08T00:00:00.000Z');
console.log(dt.tz('America/Chicago').tz('America/Chicago').format());

Expected:
Same date/time

Actual:
Date shifts back repeatedly