I sent below to KLM who said it’s correct,as you can see it’s different to what I expected ie result 72 hours before departure.

Anyone flown klm and had experience please ?

Thanks very much

If you have a transfer in Amsterdam, you only need 1 NAAT (PCR) test result that's taken within 72 hours before arrival in Amsterdam “

This is from your website I am flying with you from Bangkok to the UK on Tuesday

I just transfer in Amsterdam to Birmingham are you sure the above is correct ?

I have always been told the test is that the result must be 72 hours before I board my first flight.

Therefore the above is different and may make it more difficult to get a COVID test for the right time in Thailand.