Bad judgment :isValid

[KilianShen]

Describe the bug
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Expected behavior
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Information

• Day.js Version [e.g. v1.11.13]
• OS: [e.g. win]
• Browser [e.g. chrome 113]
• Time zone: [e.g. GMT-07:00 DST (Pacific Daylight Time)]
  

[RyanV-Souza]

I don't think this is a bug, because when we start a Date Object with a number, it is read as if it were milliseconds. For example: JavaScript is based on Epoch Time, so new Date(0) is like 1970-01-01 00:00:00 and new Date(1000) is like 1970-01-01 00:00:01.