Yes, they've been updating the vaccine every year to match currently-circulating virus strains. This is about an additional update coming out this fall.
Pretty much the same thing is done with flu vaccines, where you need a periodic update for it to be effective.
It sucks that we're unlikely to get a vaccine targeting a difficult to change part of the virus by the established mRNA makers. We would probably need a new entity to do it.
I don't know whether they even had any data on change difficulty. I think it was more like - we needed a vaccine yesterday and Moderna and BioNTech had the mRNA technology just ready to be able to spin up a vaccine quickly. And that was good enough to save a lot of people from severe disease.