It's known as Neubrutalism or Neo-Brutalism: Modern version of 1950s Brutalism. The idea is to be "brutally" raw and unedited (even though it takes great effort to make something look unedited) to convey a sense of authenticity. You may have also seen that style of "raw"/"unstyled" style reminiscent of the 50s-70s that's taking over modern fashion trends, for example with jeans and oversized t-shirt styling.
A good article on Neubrutalism: https://www.designstudiouiux.com/blog/what-is-neubrutalism-w...
Prior Hackernews post: https://news.ycombinator.com/item?id=31106892