Heard about this first on the wiki page of Kathleen Hanna . Whenever you use any filters or methods to make your music sound like they have been recorded on some old cassette, it’s called lo-fi ( as opposed to hi-fi)
Read more here – https://en.m.wikipedia.org/wiki/Lo-fi
https://en.m.wikipedia.org/wiki/No-fi
https://en.m.wikipedia.org/wiki/High_fidelity