An issue we're coming across when importing DXF files into Illustrator 2021 now is that line weights within DXF files that are imported aren't getting maitained. So before, we would see different line weights across the file, which made it easier to read certain things in the CADs we received (most noticeable in UPC line weights). However, now we're getting a single line weight across the entire file after it gets imported. This issue didn't seem to impact DXF files that were imported before AI 2021.
See screenshot for an idea of what I'm talking about.