Seems like a problem with the EASA and FAA (too) that the issue was only found now.
The FAA in turn had been systematically delegating parts of the certification back to the manufacturers themselves, and obviously have not provided enough oversight.
After the crashes the EASA have obviously determined they need to redo the verification work themselves.
For example, I worked on a program where we certified the glass cockpit upgrade for the US Navy trainer, T-6A to T-6B with Transport Canada, the aircraft with the new avionics was certified by the FAA, and the whole system was then accepted by the US Navy. Satisfying all 3 stakeholders at the same time often proved difficult.
EASA trusted the FAA to do their job and actually check the plane before certifying it. The FAA instead gladly outsourced the certification to...
... Boeing.
Which ultimately leads to the loss of reputation for the FAA, which is why EASA is now checking the plane themselves and finding numerous faults with it.
It's like University A would tomorrow get rid of all teaching assistants because it's cheaper that way and just have students self-grade their exams. Everyone will hence have only A+ and everyone is happy. Until finally a lot of really bad University A students will leave the job market unimpressed and thus hurting the reputation of University (FA)A.