Actual explanation: these squid are transparent normally, but can turn on a dark pigmentation when that is a more effective camouflage. Being transparent works quite well most of the time, but if the predator has its own light source (as several deep-sea predators do) then their transparent state becomes a problem, because it's relatively reflective compared to the water around them. In this situation, turning on the dark pigment helps them blend in with the dark water better.

Source: Zylinski and Johnsen "Mesopelagic Cephalopods Switch between Transparency and Pigmentation to Optimize Camouflage in the Deep"

If squids can turn transparent, why do they bother with all the colors and camouflage? Maybe it's just because they like to show off

Interesting. Now, who do we thank for this post? checks notes

What about their blood and organs and anything it had recently eaten? How does 100% of it turn transparent

Not even humans have yet figured out how to reproduce a Colorchecker Passport.

Squids been doing this for millions of years before humans started to science

I see Paul is up to his usual shenanigans again