I think there are several factors at play. First of all, the 737 MAX is getting scrutinized extremely thoroughly now. Whatever went wrong with the original cert

I think there are several factors at play. First of all, the 737 MAX is getting scrutinized extremely thoroughly now. Whatever went wrong with the original certification, authorities are looking with extra attention so they are not missing anything this time. Then I think, that as a consequence of the analysis of the two crashes, in general a better understanding of certain flight states has been reached. In the light of this better understanding, other bugs might be discovered which previously have been missed.