STPP
Miele used to have an article on their site about banning STPP in dishwasher detergent. It was basically saying it was more important and difficult to replace in a dishwasher than in washing machine detergent, and that dishwasher detergent only used a small amount so had negligible contribution towards phosphates in waste water.
I've been thinking about trying cheaper tablets and adding STPP myself. Lidl own brand dishwasher tablets were much cheaper and worked almost as well as the premium brands before the phosphate ban, but the phosphate free version was rubbish. With the amount of untreated raw sewage now illegally dumped straight into our waterways since the water companies were privatised, the ban on phosphates seem pretty pointless here.
One of the very worst dishwasher detergent I've tried was a very large box of low end new formula Finish powerball classic tablets, I bought several years ago, which the retailer had apparently imported from Poland, post the phosphate ben, Which left a grey residue, that was difficult to scrub off splattered over knives and forks and other stainless steel items in the dishwasher. I believe the residue was whatever they had substituted for the STPP, possibly a zeolite.
Another bad one was a liquid detergent my mum was given as part of a trial a long time ago when dishwashers were far less common in the UK. I would put the dishwasher on a timer so it ran during the small hours on cheap rate electricity, and it turned out that the liquid detergent sitting in the dispenser for all that time, had attacked the bottom section of the rubber seal on the detergent flap and was leaking out and running down over and also attacking the rubber seal between the detergent dispenser and the stainless steel door, letting detergent and wash water get in the door and rot all the wiring eventually tripping the power. I had to replace most of the wiring inside the dishwasher. Probably wouldn't have been a problem for any more modern dishwasher with more chemically resistant rubber seals.