In the absence of further information.......it is your design so you are the best one to answer your Q.
btw - looking a the image, the data and address lines look multi-driven. The I2C master should only be the source driving them.
Grounded nets often mean that the signals/lines are not connected to anything in your HDL (ie. the signals/lines are not driven). So, synthesis has simply tied them to their initialized value of 0=GND.