> Could be, but tests graph (below) does not show similarly distinct jump

Exactly the point ;) The top graph shows 200 new cases on March 30 — the date when test results came in. The bottom graph shows no spikes in positive cases on March 30 because this graph shows positive results by the date when test was performed. So in reality we have very stable 50-70 new cases per day since mid March, no spikes at all.