Unknown type of date or time in web developing

I saw in a web site request date format like this:

2020120321-20210003220330

it's not epoch. What is this date format? How can I convert it to human-readable format?

Seems like a range:

• 2020120321 - December 3rd, 2020 @ 21:00
• - to
• 20210003220330 - Mystery month 3rd, 2021 @ 22:03:30