Colours. Colours on the screens. Colours on billboards. The colours we wear. The colours of foods we see in pictures. The colours of AI loaded photos we click on smartphones. Dopamine spiking colour abuse started in glossy magazines and street posters of big fashion and food companies, way before social media existed like post 2000s.

The abuse of human psychology using colours is arguably the worst crime committed in the human history, for which specifically USA is responsible. Never before Edward Bernays did this human psychological abuse exist on Earth, and never before has there been an advertising ultracapitalist machine like USA. (I recommend watching Century of The Self by Adam Curtis.)

The typical answer to OP's post would be social media, but the ingredients of social media are human psychological abuse using dopamine spiking colours, infinite scrolling and Vine-style short content. (Tiktok is credited with polished recommendation algorithm, but Vine originally brought about this disease, later in the form of Snapchat Stories, then Instagram stories and then Tiktok. Tiktok is merely the evolution of FrankenVine.)

If you want to conduct a self experiment, just try this for a day.

• On Android and iOS, you can use grayscale mode on your phone screens
• On Windows 10+, you can search "Adjust Color Filters" and enable grayscale filter using Win+Ctrl+C key. (Windows 7 has a tool "Negative Screen" https://zerowidthjoiner.net/Uploads/negativescreen/Binary.zip)
• On Linux, the easiest way for GNOME users is to install the GNOME extension "Colorblind Filters". On KDE, you can install Grayscale Effect or similar tool. (For LXQt users, here is a method https://nevyan.blogspot.com/2018/08/enabling-grayscale-in-gnome-kde-and.html)
• On Mac, you can access grayscale mode using Accessibility settings.

You will be shocked how accurate my observations are, and how less people even realise how long this has been going on for. Literally more than a century.

Edit: since some dishonest, malicious and ignorant people have downvoted and gone ahead to claim its stupid and baseless, I will tell them that their existence is a liability, because they defend these neurological and psychological abuses. Absolute wretched people.

The effects of colours having different kinds of psychological effects are well documented. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4383146/

The neurological and psychological abuses employed on digital screens akin to slot machines is also documented, since social media apps and most audio visual content on computers employ same neurological hack techniques as that of slot machines.

https://neurosciencenews.com/visual-sound-slot-machines-15816/

https://www.fastcompany.com/3046149/applying-the-addictive-psychology-of-slot-machines-to-app-design

https://www.sciencedirect.com/science/article/abs/pii/S0166432812006456?via%3Dihub

https://www.gatewayfoundation.org/addiction-blog/how-gambling-affects-brain/

Irresistible by Adam Alter is a great book on addiction.