The token was Lucky Block
https://poocoin.app/tokens/0x2cd96e8c3ff6b5e01169f6e3b61d28204e7810bb
I was not able to buy within the first five minutes. Perhaps the slippage should have been even higher ...
After those five minutes the transaction worked fine with my slippage value.
Unfortunately I don't recognize that error, too long time ago ....
Is a too low transcation fee another possible explanation?