In most cases this is mainly due to the excessive buildup of tile cleaning solutions you may have used to clean it in the past few months or even years.
How to make dull ceramic shine.
In a bucket add one gallon of warm water and mix in one tablespoon of rubbing alcohol.
Over time the tile can grow dull even with regular cleaning.
This is a job you can easily do yourself so give it a go first before you do anything else.
Often this is due to a buildup of cleaning products used on the tile in the past.
How to shine ceramic tiles.
Dunk your mop in the solution and squeeze it out until your mop is damp.
Mop up your floors adding a little pressure to wipe away grime.
Ceramic tile is lovely and easy to care for but over time it can appear dull instead of shiny.
While it might be tempting to use a commercial product such as a floor wax that makes claims to shine tile floors often those products build up on the tile and discolor making the tile look even worse.
For ceramic tile in the bathroom shower or bathtub it can actually happen very quickly.