I arrived AMS from the US on Monday 7 June on my way to another Schengen country without a test (since AMS transfer didn't require one, and my destination Schengen country didn't either for fully vaccinated pax). On arrival in AMS we were met by Dutch personnel at the jetway door asking to check our PCR tests. I told him that I didn't need one for transfer and showed him my onward boarding pass. His response was "you are right, you don't need one for transfer, but most passengers have one anyway so we are asking to see them..." (??!?)...and then I was allowed to go on my merry way....quite strange actually....

Edit: I just checked the Dutch government website again, and under the section "Negative Covid-19 Test result: rules when changing planes" and it says:

....If you start your journey in a high-risk area or country and change planes in the Netherlands,
- you do not need to show a negative NAAT (PCR) test result or rapid test result on arrival in the Netherlands
- a transfer is when you change planes and continue your journey within a few hours, and in any case within 1 day without leaving the airport where you transfer...