People keep going on about the racism towards M but in all honesty where it the evidence? I read alot of the 'decent' press and never saw anything to do with her colour, ever.
I did read about- and saw- how she was sometimes dressed incorrectly for State occasions and times where she didn't behave with protocol on occasions and sometimes this involved the Queen.
I read about her anger over which tiara she wanted for the wedding and Harry's tantrums and his call that 'what M wants, M gets' even though the queen offered her a more suitable tiara
I doubt the anti- M lobby was never about her race but about her behaviour which at times was 'difficult' and showed a lack of respect or understanding for tradition and the right behaviour.
I also think that a lot of the public who had a very soft spot for Harry saw him being controlled by a woman with her own agenda and who found it impossible to abide by royal conventions, compared to the freedom of her life in the US.
Unlike Diana who was only 19 when she met C, married at 21 and a mum soon after, M was an older woman. she ought to have understand the downside of royal life. Privilege comes at a price and soon it was clear she wasn't willing to pay that.
Who knows how much effort she really made, or how much she decided long in advance that a title of Princess was her goal and hoped she'd retain it even if they left the UK.
This is maybe why people are against her, not because she is mixed race.