Flew out Thursday and back today. Two days before travel I was given the official Dutch questionnaire for entering the Schengen area which raised the alarm - you have 270 days after your second shot before they require a booster.
Large crowds at passport control on entry and didn't see anyone have their extra paperwork looked at (I had a letter from a director of the Dutch parent company stating I was a critical worker). There was also a mask mandate within Schiphol airport that was widely ignored. Another colleague was lucky enough to have the official NHS certificate for catching Covid giving him 180 days post infection - he had had a PCR test - I didn't get any certificate for my lateral flow test though it appeared on the NHS app.
HTH
Zeb