Have you also checked your song externally before uploading to SoundCloud? I did this a couple of times, and everytime there were different values compared to internal measurement. Not that bad like on SC, but quite different, especially in terms of TP. I also checked some of my favorites from my music collection (professional productions), and it’s the same game. In those cases TP is always between +1 and +5. On SC it gets worse. Imagine what happens if you don’t limit loudness and TP. Clipping all over the place. So it’s required to mix properly and master your sound appropriately, then you’ll get an acceptable result on SC.