Basement Cat

Challenge:

Hi, me iz Basement Cat!

Here iz flag: 5jsnZDgv9EfFeoGXZrFurdz7MWAnK2WaPfszFadr

Solution:

The bolded word "Base" in the challenge description was a clear hint that the flag has been encoded with a binary-to-text encoding scheme (i.e. Base-X).

Pasting the string into CyberChef auto-detects it as Base58:

The accepted flag was, he2021{meow_nice_to_meet_you}.