repetitions

echo "cat enc_flag | base64 --decode | base64 --decode | base64 --decode | base64 --decode | base64 --decode | base64 --decode" > script.sh

sudo chmod +x script.sh

./script.sh

You could also just put the text from the enc_flag file into cyberchef. You can just put decode from base64 many times until you see the flag. Cyberchef might also give you the magic pop-up to decode from base64. Also if your not in linux and you can't just do cat enc_flag than you can always open the file with notepad++.

Flag: picoCTF{base64_n3st...e523f49}