I am not dismissing any claims, but having a >90% party allegiance based on ethnicity is such an extreme situation, that ascribing reversions to one aspect of the left (which, true enough, the right wants to focus on), is just projection and also an exaggeration. I saw a recent interview with David Shor [1], who said that the conservative/progressive split in the US (based on self-identification, IIRC) is about 60/40 across all ethnicities, but that many vote based on reasons other than ideology. But now we're seeing a trend across the board, where people's votes increasingly align more with ideology. So many conservative blacks vote Democrat, and might be shifting away because of a general emphasis on ideology.
That actually makes perfect sense of the "walking away" talk, though. It was extreme and unusual in the first place that ardent conservatives would vote for the same political party as socialist activists based solely on race or identity. That was really weird, actually, and an end to that kind of thing is just "reversion to the mean" of people voting for what they actually believe in.
Sure, but they were attributing it to a very specific cause rather than general ideological disagreement, not to mention that the number of black people walking away from the Democratic party is not large, certainly compared to the level of support.
[1]: https://www.youtube.com/watch?v=SQ8UDzUvMg0