Some people posting to this thread or reading this thread might be interested in the discussion here and here about the use of the word "lady" in the UK and in the USA.

[the "heres" being towards the end of the same immensely long thread about British fascism - you might be in for a long wait if you click on those links]

"Lady" has such a multiplicity of connotations you are not going to get the simple answer you seem to be looking for. It would be quite possible to imagine very similar contexts in present-day British usage where one use would be insulting, another grovellingly sycophantic and another neutral, and you'd need to know quite a bit about the speaker and the person spoken about to figure out which was which.

But there's no correlation with race involved, except in the very indirect sense that there haven't been many non-white women entitled to claim formal modes of address reserved for the peerage until recent decades (probably the first would have been the wives of bishops of the Church of England). Those modes of address only account for a tiny fraction of the occasions when the word is used.