Yes, libraw20 breaks libraw19 because the deb control has libraw19 set conflicts and replaces. Replaces shouldn't be set because it doesn't overwrite anything. I'm not sure if there is actually a conflict but there doesn't seem to be.
You can get it to install if you download the deb:
apt-get download libraw20
Unpack it:
ar x libraw20_0.20.0~202008211452~ubuntu20.04.1_amd64.deb