Hmm. Don't know why but it could be due to popularity of Node in general. Going with something that is popular is often the best way to ensure you'll always have candidates to hire.

Different set of companies, because I get spammed for .NET, Java and C++ backend positions almost every day, and zero node stuff.

thanks for the reply. and what stack, tools do companies ask for ML/AI recruiting?

Python / Tensorflow / PyTorch mostly. And then other specifics depending on the AI/ML discipline or problem space.