We found the reddit user that posted the post and by looking through her post, we found another post named " CTF " with a comment " code_nerd "
We realised that as we scroll through the post, the first letter of each caption forms the word "GITHUB". Hence, we assumed that we have to find "code_nerd" in github.
I managed to locate a repos named code_nerd after scrolling through a few pages and found a text file named flag.txt