The new public key uses the same private key as before, so that fingerprint is still correct.
From a fresh docker pull, I ran these commands and they worked correctly for Ubuntu Bionic and Focal, targeting Melodic and Noetic respectively:
$ docker pull ubuntu:focal
$ docker run --rm -it ubuntu:focal
# apt update
# apt install -y gnupg lsb-release
# sh -c 'echo "deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list' >/dev/null 2>&1 \
&& apt-key adv --keyserver 'hkp://keyserver.ubuntu.com:80' --recv-key C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654
# apt update
# apt install -y ros-noetic-catkin
Perhaps try removing any existing key prior to running the import step?
apt-key adv --keyserver 'hkp://keyserver.ubuntu.com:80' --delete-keys C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654