I think it's less that it's gaining in popularity than that we're seeing some backlash from the people who aren't liking Rust as much as they wanted to. The boring truth is still that if you have a "bottom layer" task to solve that needs access to hardware details (be it instruction formats, SIMD algorithms, MMIO drivers, system-dependent stuff like container management, etc...) C remains the quickest and easiest and frankly the most fun environment to do it in.

I mean, there's a reason why Karpathy is hacking on "llm.c" as part of his "clean up the world" project and not "llm.rs".

Is that a good thing or bad thing? I won't engage. But I think that's where the psychology is. For myself, I genuinely love C in a way that it's clear I never will Rust.