The rot13 is a well known Caesar cipher, see https://fr.wikipedia.org/wiki/ROT13.
Python codecs module can encode and decode rot13:
import codecs
def rot13_decode(ciphertext):
return codecs.decode(ciphertext, 'rot_13')
# Example usage
ciphertext = "SPFP{rq24p7sq86p2s0515366}"
plaintext = rot13_decode(ciphertext)
print("Decoded text:", plaintext)