I’m genuinely on 140 downloaded themes, trying each one of the 188, and I still haven’t found it. Is it a collection of css snippets? I’ve also seen a similar one in a video.
If you can’t find the theme - it may just be custom callouts and altering of text and links - you can make your own by following these steps:
The Lucide icons are here: https://lucide.dev/, but that 
one looks different from the lucide one, so maybe it’s a custom SVG.