What's wrong with the crossbow bolts in The witcher 3?
Solution 1:
On the PS4 version with patch 1.23 the normal bolts display as +400 silver damage only when underwater. Otherwise they display as +4 silver damage. That also seems to match the damage they do.
People do seem to have run in to a bug where the game still considered you to be underwater when you were back on land again. Possibly you have hit that.