How bad is this? (back glass cracked, sensors seem intact)

How bad is this? (back glass cracked, sensors seem intact)

I just discovered this X-shaped scratch/crack on the back plate of my series 6 watch. I don’t have apple care + (kicking myself for it). The watch seems to be working/charging absolutely normally. I am guessing this breaks the water resistance. Is there anything else that could be a problem? If I take it in for repair, is it just a question of replacing the back plate or will they have to install new sensors?