During a hackthebox stego challenge I stumbled upon a nice tool called tapcleaner by bokvamme and luigidifraia.
I converted wav files to tap with wav2tap (c64tapedecode) but wasn’t able to load them. With tapcleaner it was possible to optimize the output in a way that the tap file was recognized by tapcleaner and I was able to extract the prg’s which contained the flag.