Using dayjs.tz.setDefault with endOf('day') makes the date tomorrow

[codeBelt]

Describe the bug

If I set the global timezone with dayjs.tz.setDefault() and use dayjs.tz() with endOf('day') I get the next day.

• 2020-01-08T23:05:05-08:00 (date I used)
• 2020-01-09T23:59:59-08:00 (date I get)
• 2020-01-08T23:59:59-08:00 (date I should get)

Example Code

dayjs.extend(utc);
dayjs.extend(timezone);

dayjs.tz.setDefault("America/Los_Angeles");

dayjs.tz("2020-01-08T23:05:05-08:00").endOf("day").format(); // 2020-01-09T23:59:59-08:00 (wrong date)

Using dayjs().tz().endOf("day") works correctly but not dayjs.tz().endOf("day"):

// This works correctly:
dayjs("2020-01-08T23:05:05-08:00").tz("America/Los_Angeles").endOf("day").format(); // 2020-01-08T23:59:59-08:00

// This does not work correctly (same code above in the first example)
dayjs.tz.setDefault("America/Los_Angeles");
dayjs.tz("2020-01-08T23:05:05-08:00").endOf("day").format(); // 2020-01-09T23:59:59-08:00 (wrong date)

Expected behavior

I expect the end of day be the same of the date being passed in.

Also startOf("day") causes the same issue so I don't think it's only related to endOf("day") and startOf("day").

Information

• Day.js Version 1.10.3
• OS: macOS Catalina 10.15.7
• Browser Google Chrome Version 87.0.4280.88
• Time zone: GMT-06:00 DST (Central Daylight Time)