I'm not so sure how valid the argument about test capacity limits and underreporting is. While laboratories for PCR tests might be above capacity the 2G+ requirement (recovered or vaccinated AND tested) must have increased quick antigen tests dramatically, which also get registered and positive tests reported. E.g. to enter a public pool I had to get tested and they had a test tent right next to the entrance. The week before I could just enter with my vaccination certificate. Many people have to get tested more extensively now for work or travel. So I would be very surprised if the test coverage hasn't actually increased and declining numbers with more tests certainly looks like a good sign.