Strange behaviour with dates between 1969 to 1971

[MattStantonMBS]

Describe the bug
When using dates in the years 1969, 1970 and 1971, using operations like "startOf" results in times from other days
i.e. dayjs('1970-01-07T01:00:00').startOf('day') will result in "Tue, 06 Jan 1970 23:00:00 GMT". Years before and after these 3 years do not show the same problem

Expected behavior
dayjs('1970-01-07T01:00:00').startOf('day') should display "Weds, 07 Jan 1970 00:00:00 GMT"

Information

• Day.js Version: 1.11.0
• OS: iOS
• Browser: chrome 131.0.6778.265
• Time zone: GMT