Disclaimer: I'm not an expert on the subject so please feel free to clarify anything I misunderstood.

https://en.wikipedia.org/wiki/Critical_race_theory

There's a movement in black society that believe white supremacy is an institutional inevitability and everything must be questioned and scrutinized for any sign potential signs of racism.

Considering that the civil rights movement only took place 50-60 years ago in America this is kind of a fair perspective. Not only are there are a lot of genuine racists out there trying to undermine the civil rights movement, but there's a lot of residual problems from the racist era. Such as discriminatory laws, even if at first glance they do not appear to have any racial bias, see black voter suppression to get an idea of how something with no apparent racial bias can have a significant impact based on race. So in this sense, CRT is completely justified. It's a necessary part of the process in reviewing society and making sure everything is fair for all people regardless of race.

The problem is that some people interpret CRT as meaning that all white people and institutions cannot be trusted. Instead of the air of caution and critical reasoning I believe was the intent of the original research. It has grown beyond this into a scapegoat of reverse racism. Where you do not need to provide evidence to support your claims you can just blame institutional white supremacy. And that's not to say it's not sometime the case, but some take it an extreme where it must always be the case. Hence not needing "white allies".