Copyright avoidance is tricky. Even if you come up with a good method today, that method might not work in the future as copyright ID systems improve (e.g. you used to be able to just pitch-shift or slightly speed up/slow down a song to get past YouTube's systems, whereas now I believe that doesn't work anymore). So you kinda have to mangle songs pretty badly at this point to slip past the filters it seems. And in addition to the automated systems, there's also manual review which you'll still be susceptible to if your video/song gets too much attention. There's also ethical problems with redistributing other people's work without permission. It's not something I'd probably ever try to do tbh