Mastering music for cassette is not the same as mastering for Spotify, Bandcamp, vinyl, CD, or the imaginary “warmth” plugin some guy on YouTube keeps trying to sell you.

Cassette is a real format with real limits. That is the whole point. It has noise. It has saturation. It has reduced top-end compared to digital. It does not care how expensive your limiter was. If you feed it a crushed, brittle, ultra-wide digital master, it will usually punish you in a way that feels personal.