I don't think I'd go as far as "copying" but Deno was the first to aggressively push for web standards in server-side runtimes and certainly helped accelerate getting them adopted in that environment.
I work at Cloudflare on Workers (but infrequently work on our runtime) and I've always been pretty impressed with Deno. Their recent-ish support for built-in OpenTelemetry is something we've been wanting to do for a while and have been working on, but Deno was able to build a good implementation of that in that time.
The behavior isn't entirely the same and reaching 100% parity is a non-goal, but there are a few things to note.
This is still a very early implementation and there are undoubtedly issues with the implementation that weren't covered in next's original test suite (and thus not inherited) while not being obvious enough to pop up with all the apps we've tried so far.
As for why it's so much smaller, by building on top of Vite and their react + rsc plugins there is a whole lot of code that we don't need to write. That's where a significant portion of the LOC difference comes from.
Doesn't that just move the goal post though? Instead of using your GPU vendor for the fingerprint they can just hash the output canvas after they a bunch of odd rendering calls, getting a hash from the quirks of your graphics driver and GPU hardware.