Amateur question.

Now this might be basic for some but for some reason I can’t wrap my head around this question.
I have a portion of money invested in the Ishares Core SP500 listed on Xetra (European so can’t buy the American listings). Can anyone explain to me how the ETF that should track the SP500 can differentiate so heavily from the actual index.
As of now the SP500 are up YTD 4,82%
While the ishares etf is up 1,95%
The dollar/euro is down 1,72%
The cost of the fund is only 0,07% so that can’t make up the difference.