[Yachts]

I'm thinking sniper rifle from a long distance.  Due to the distance of the shot involved. The relative humidity and ambient temperature couple with the angle created a nick that due to the high rate of deflection shattered the glass.
What we really need to analyze is the reason behind the shot.  I'm betting a former disgruntled lover who was not invited on the road trip coupled with high amount of jealousy directed towards Baxter and Ro. This created feeling of inadequacy and cause the person to realize the quality of physical attention they had been receiving was about to drop to an inadequate level to support the continued amount of emotion attachment.

In reviewing the video from Bills dash cam I did find the following.