N.B. Mueller’s replacement, Ladaria, is 73 years old; 4 years older than Mueller.
Ladaria has been secretary of the CDF for years (appointed by BXVI). He’s seen as more or less orthodox, but with a tendency to statements that can be interpreted as universalism and indifferentism, although at the same time, he has opposed these specific things. So he doesn’t represent a real change, IMHO.
What it does show is that the Pope thinks the CDF is meaningless and has no control over his statements. It is the custom of popes to pass formal documents - and even less formal addresses, etc. To the CDF for vetting. After the CDF suggested major changes to AL, the pope not only refused to accept the changes, but stopped submitting his writings to the CDF at all. The appointment of Ladaria is just a confirmation of the fact that it is yet another Curial office that Francis has decided to ignore.