Maybe it will be useful to someone. This code makes rounded corners in the "author" block on the discussion viewing page. Just instead of "360" enter the number of the block that is on your site.

.to-white {border-radius: 1rem}

#bx-page-block-360 .bx-base-pofile-cover-image-wrp {border-radius: 1rem 1rem 0rem 0rem}