It was DeepSeek, the Mobile App that consumers (including stock traders, analysts, & investors who don't follow the day-to-day developments within the LLM field) could download from App Stores that had the 'moment'.

And it was the AI chat app that led the professional talking heads to learn about the Language Model (DeepSeek R1) powering the Chat App, the Scientific Paper explaining the techniques used to build the core model (Deepseek V3), and the said paper's claims of the model being developed at a far cheaper amount than comparable Western models.