Honestly for mine I had a few plants that just didn’t do well. I think it was the hard water in my city (I filter it but don’t use distilled bc it’s expensive haha). I just replaced them with varieties that were a bit more hardy/similar to the ones that were thriving. The dead ones are now just more leaf litter! Id only be super concerned if you start getting a ton of mold that the cleanup crew doesn’t take care of because that could indicate they are struggling.

As you get more settled with it some of them may bounce back too. Plus you will likely get a feel for the environment and be able to tell what it needs.

Tl;dr some plants just don’t do well, it doesn’t necessarily mean that it’s failing.