This post refers to the puzzle contest held by 
@friendlymoose/contest-about-colors
Disclaimer: I'm British so I'm about to use the word "colour" a lot. And probably less "z"s than you'd expect if I was American.
Like most people in the comments I started with the obvious cipher. While I wasn't aware of Hexahue, I could tell that the white gaps were spaces and the black and white tile was probably a symbol. A lucky Googlesearch of "6 color squares cipher" revealed the decryption key and sure enough it was a simple alphabet substitution. Easy part done.
This is where a lot of the people in the comments got stuck. In onealfa's last puzzle the answer was found using an online stenography tool and a password.
I also thought this might be the case so uploaded the puzzle picture to https://www.mobilefish.com/services/steganography/steganography.php and entered the password 1alfaquiz (also 1ALFAQUIZ) just in case) but got nothing.
This lead me to backtrack and take another look. "Go find the file" hmmm. The latest puzzle came out very soon after
No.png file was safe. There were a few in onealfa's last contest so they were uploaded and both passwords attempted. Even FriendlyMoose's signature pic wasn't safe. But no joy. Nobody has used old posts to hide clues yet. Back to the drawing board.
Secrets, plural. I opened the image in notepad and checked for any code at the end, but saw nothing. And at this point I knew it was something new.
So the image was opened in gallery and contrast/exposure/saturation levels played with. Nothing jumped out but the low saturation "ABOUT COLORS" wasn't sitting right with me. Everything in that image was placed there on purpose, so Moose had to actively decided to use those colours.
Nobody but the elderly uses these colour tones
I remembered that hex codes were used in the last puzzle, and that colours can be assigned a 6 digit code.
It was late night for me and I was on my phone, but it seemed likely enough for me to get out of bed and boot up the laptop. The only image software I had was MS paint so it took a little while longer by sampling the colour and converting it from RGB values to HEX, but as I was doing it I had a really good feeling about it.
687474 70733a 2f2f74 696e79 75726c 2e636f 6d2f6f 6e6561 6c6661 717569 7a2f20
At this point before translating the code I knew it was something. The grey colours in the text were different Hex codes they had been picked deliberately.
After using an online hex to text translation tool I was left with https://tinyurl.com/onealfaquiz/
The tinyurl was a link to a onedrive that held the image in a zip file. Upon downloading it my laptop refused to open it, and winrar on my phone just crashed.
After a lot of frustration the android file viewer asked for a password and I could input the password I found in the first step. Aaaand relax.
Success!
While working on the puzzle I wasn't really worried about being beaten to the answer. (I was mostly under pressure to finish because I had work the next day)
But once you have the answer let me tell you, paranoia sets in and even a tiny delay like taking a few seconds to upload the image feels like someone is about to beat you to the punch. There's a lot of very capable people on this site and I knew someone would be close behind.
Thanks again to