Benchmark not correct in performance charts

Hello,

I really like Portfolio performance.

Only the benchmark option seems incorrect when I add it to the performance graph

For example it shows that sp500 returned 37,48 % in 2021, while this is 28% actually,

same for nasdaq and XBI.

Any suggestions?

27% in USD, 38% in EUR. (33% in CHF, 30% in GBP.)