There's also a fair bit of (alleged - who knows) Turkish fans saying that it's a pretty standard sign which has been taken on by the far-right group.
I don't know enough to say either way. If it was the sign it's not right and he does have previous as he was involved in that Turkey celebration a few years back.
However, I imagine if it was Richarlison who had used a controversial symbol in a celebration, then our fans would be defending him.
Basically, it's because Tosun isn't very good that people are out for him. Whether he made the sign or not.
I don't think he should be playing for us because he isn't very good. It's crap that we're still relying on him.
FWIW, I actually thought he did okay today. Took his chance early, scored from the next chance he had. Should have done better with the one in extra-time.
If he's made that celebration it's wrong but it's up to the club to investigate further. Not fans to make up their minds that he's definitely in support of a far-right group just because he's not very good.