Why is the CSPX IE00B5BMR087 underperforming the S&P 500 Index by so much?

CSPX has made 1.3% YTD, while the S&P 500 index is up 4.32%. I know it tracks an ESG-screened version of the S&P 500, but could ESG exclusions and tracking error alone explain this large gap? Or are there other factors, like currency fluctuations or dividend treatment, at play?