There’s evidence that Europa’s subsurface ocean is too sulfurous for life to exist. It’s thought to be similar to Io near the core, with undersea volcanos spewing sulfur compounds. They’d be too caustic for single cell organisms.
I always find these statements annoying. However, I will correct the annoying part for you. :-)
“...ocean is too sulfurous for life, AS WE KNOW IT, to exist.”
The height of hubris is these scientists believing they know it all about LIFE! NOT!