week() with timezone is incorrect. (Europe/London)

[jetzhliu]

Describe the bug

Performance is inconsistent with momentjs.

see https://codesandbox.io/s/blue-platform-4zlug?file=/src/index.js

console.log(
  'dayjs: 2021-01-05',
  dayjs.tz('2021-01-05', 'Europe/London').format("gggg-wo"),
  dayjs.tz('2021-01-05', 'Europe/London').week()
);

// output
// dayjs: 2021-01-05 2021-6th 6

console.log(
  'moment: 2021-01-05',
  moment.tz('2021-01-05', 'Europe/London').format("gggg-wo"),
  moment.tz('2021-01-05', 'Europe/London').week()
);

// output
// moment: 2021-01-05 2021-2th 2

Expected behavior

output dayjs: 2021-01-05 2021-2th 2

Information

• Day.js Version 1.10.7
• OS: MacOs
• Browser chrome 96.0.4664.93
• Time zone: GMT+0800

[jetzhliu]

the same problem here, only on utc 0.

dayjs('2022-01-23').utcOffset(0, true).format()
// print: 2022-01-23T00:00:00Z

dayjs('2022-01-23').utcOffset(0, true).add(1, 'minute').format()
// print 2022-01-22T16:01:00Z
// !!!

dayjs('2022-01-23').utcOffset(1, true).format()
// print 2022-01-23T00:00:00+01:00

dayjs('2022-01-23').utcOffset(1, true).add(1, 'minute').format()
// print 2022-01-23T00:01:00+01:00