This 23 January 2020 Dutch video, about birds attracting birdwatchers and photographers, says about itself (translated):
The seven flamingos were spotted on Tuesday at Benthuizen, a day later they were noticed by walkers in Pijnacker. According to nature conservation manager Cor Noorman, this concerns six Chilean and one European flamingo.
The birds are probably from a nesting colony near Winterswijk, just east of the Dutch-German border.
Dear Kitty. Some blog 
Amasing to find flamingo’s in the Netherlands in winter. But afterall what kind of winter is this. If this is climate change then it did bring one good thing; Flamingo’s but just this one. It brings just troubles.
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Flamingos have wintered in the netherlands before:
https://dearkitty1.wordpress.com/?s=flamingo+grevelingen&submit=Search
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