I haven't had much to add to this reply chain- y'all are both speakin my language 👌- but I also feel part of why STC!Sonic is Like That is because, in addition to the short temper and his baggage, STC!Sonic is a typical British Lad, and British Lads love Banter With The Boys™️;

His jokes and jabs are harsh for sure but they are meant to be jokes in-universe a lot of the time. Its actually a pretty good British Take on the whole "he's got an ATTITUDE!!!" thing- which is part of why it lands for so many of us. I can see why that might not translate to fans in other countries