rotation

There was just a text file with this:

xqkwKBN{z0bib1wv_l3kzgxb3l_7l140864}

Based on the challenge name "rotation" I immediatly thought of rot13 cipher in cyberchef. It wasn't that but when moving up and down in how much to rotate I eventually got to "18" which gives the flag.

Flag: picoCTF{r0tat1o...d140864}