TDS is derived from EC (electrical conductivity)
Tds/ec measurement does not tell you what is dissolved, just how much electrically charged particles are in solution. Without testing a sample there's really no way to be sure what is in it.
As I understand it you still have to watch the EC of water you apply, including liquid fertiliser mixes ( and ultimately dry fertiliser that dissolves in water ).
Basically if NaCl salt has an EC, then so does CaCl, MgCl, and also MgSO4 etc etc. all common component of fertilisers.
Yes some are going to be beneficial nutrients and some more harmful, but a very high EC from any compound can be a problem, particularly in pot plants.