This Google Trend graph shows an increase popularity. The increase has been fairly linear since 2014 but there were notable spikes in late 2021 and early 2022
Agreed. Nix always means Nix Package Manager unless NixOS is specified. Its hard to distinguish `Nix` from `Nix package manager` in google trends though, so the "NixOS" trendline might be the best proxy for popularity of the entire ecosystem.