The only source for this a could find was an old paper on iOS 8, while this more recent one https://arxiv.org/pdf/1703.02874.pdf https://arxiv.org/pdf/1703.0287

The only source for this a could find was an old paper on iOS 8, while this more recent one https://arxiv.org/pdf/1703.02874.pdf https://arxiv.org/pdf/1703.02874.pdf seems to suggest the randomisation works as intended for unknown networks...