There may be an issue with artificial flamingo feed, if they are in the UK and so presumably captive birds... ISTR something about flamingo's not being naturally pink, but white, its the shrimp they feed on in Africa that gives them the colour; not feeding on the same shrimp in captivity, they get food supplements with artificial coloring's in them, possibly saturating the colour, err., artificially naturally.. err. homeopathically? Err... well, non electronically and in the subject you see! However!
The Problem'?!?! You know what? I don't think there really IS one!
At first glance, my reaction was its nicely exposed. Exposure, you seem to be implying is 'serendipitous', to my eye, is what I would have been aiming for, possibly a tad less under, but in that region, to get the detail in the water and the plumage of the bird while avoiding blowing high-lights in reflections, and saturating the colours in the subject against an otherwise rather monochrome back-ground.
I LIKE the shot as is. I don't think it looks particularly 'over vibrant' or un-natural.. I would be very pleased and be calling it an 'effect' and hoping I could do it again, rather than calling it a 'problem' and trying to avoid it!
I think the <s>'problem'</s> effect is most probably the quality of the low angle light, raking across the texture in the water, and 'golden-hour-hue' tinting the plumage, and I'd struggle to replicate without that, just on 'settings', but I would have been well chuffed to have got that <s>'problem'</s> effect clean in camera without a polarizer giving me a dilemah between getting colour saturation and flattening the water reducing reflections from it.
There's no such thing as a 'correct' exposure, only more or less pleasant ones.. and this is a pretty pleasant one, I think.