This concept is called 'Zero-Width Steganography' which has not been covered in any CTFs, There is a library for decoding https://github.com/offdev/zwsp-steg-js or can be manually decoded. There is nothing to guess, as Intention is players will open console & look at the ASCII text which isn't all ASCII but has unicode as well
flag{w3_gr337_h4ck3rz_w1th_un1c0d3}