GOLDENCORE IS FRAUD! DON'T INVEST!
Apologies for writing in English - I don't speak German, but a similar thing happened to me and I lost a considerable amount of money and want to make sure others don't make the stupid mistake I made. Like you, I met someone from China (Hong Kong) who said she knew about this new crypto with huge potential called Goldencore. Google (as you know) shows nothing for it - she said it's because it's still in the hush-hush stage but she has great advice on how to get the most out of it. It's a long story so I won't bore you with the detail but the short version is that I followed her advice, made some money then, when I invested as much as I could, she gave me advice that wiped out my entire investment in a few minutes.
My guess at this stage is that the GDQ app is fake and you're transferring your BTC to scammers, who then make some fake trades and when they think they can't get you to invest any more and then make you "lose" your money.
