Check your faucet aerators for bits of debris, that would be you dip tube gone if it is metal or plastic. If you have hard water, it could just be minerals.
The problem with putting in a new dip tube is you must have head room over the water heater that equals the length of the water heater. The bigger issue is the old tube is still lying on the bottom adding bits of plastic to your water supply.
So, if the dip tube is gone, new water heater since yours is 12 years old. Disconnect the cold supply to find out.