Treat TDS as a clue
A TDS meter estimates dissolved material from conductivity. It cannot identify whether the reading comes from minerals, fertilizer, waste, or another substance.
Check the meter calibration and compare with recent readings. Test GH, KH, nitrate, and other relevant parameters to understand the change.
Find the cause first
Review top-offs, evaporation, fertilizers, salts, and recent water changes. Mineral concentration can rise when water evaporates and is replaced with water that contains more dissolved solids.
Do not dilute the tank rapidly just to hit a target. Once the cause is clear, use a gradual plan with compatible replacement water.
For your own tank
Compare the current reading with your own baseline, not a number from another keeper's tank. Check the probe and test the water source. A gradual rise can come from evaporation and mineralized top-offs, so trace the routine before diluting.
Use these as general hobby references. Test your aquarium and confirm product guidance before making changes.