Here's the best video I have seen about transformers [1]. It is made by Welch Labs. It talks about DeepSeek and what their main innovation was, but it covers transformers in general too, and I couldn't find any other better description of transformers.

Also, here's an interactive "transformer explainer" that is absolutely mind-blowing [2].

[1] https://www.youtube.com/watch?v=0VLAoVGf_74

[2] https://poloclub.github.io/transformer-explainer/