“Good design is invisible” is a fairly smug cliché among designers.
It is based on the idea of Affordance. The idea that some design can be so intuitive, so obvious that people just use the product or service. They do not notice it as they benefit from it.
However, there is a flip side to this.
It is Accommodation.
Bad design is invisible too.
People get used to products and service that do not work or simply function badly. They work around the problems with hacks. They become inured to the crappiness and just use whatever is there. Better that something gets done than nothing get done.
This is why talking about the design of new services and products can be tricky. People may not realise there is a problem because what is happening badly is imperceivable to them.
So do not judge success or failure based on the invisibility of the design. People can use a product or service which is good or bad without noticing it at all.
Affordance and Accommodation are two sides of the same coin.
Force invisible things into being explicit. Make them visible to ask whether they are good or bad.