It is a misleading question because it is not about color, but about contrast.
Is colour alone enough to convey warning?
Yes, if these colors are strong enough to show a unique concept. In maximum saturation, with a simple use of color, states can be hinted at. Anyone can easily find concepts such as danger, alert, caution, ok, accepted and finished in the following range of colors, with a minimum margin of variation:
The same example using the same colors but desaturated totally changes the perception:
From which it is understood that the only way to demonstrate specific concepts with elements as subjective as color, is only achieved with maximum contrast.
But this is not the case of the example image of the question that presents two colors with a very low saturation before which the correct question would be:
Desaturated colors offer enough contrast to convey warning?
In this case, the answer is no, desaturated tones go through a color choice and can hardly carry such an extreme concept as alert or danger, so my recommendation would be to point to other resources but always based on CONTRAST.
On the other side, there's an added element. In the image there are two orange backgrounds, one with a black line graph and one with a light blue pictogram. Both oranges look different, the one on the right looks darker. This is for Simultaneous contrast which refers to the way in which two different colors affect each other. The theory is that one color can change how we perceive the tone and hue of another when the two are placed side by side.