https://support.ookla.com/hc/en-us/articles/32139787616141-Ubuntu-24-04-noble
Workaround:
sudo apt-get install curl
curl -s https://packagecloud.io/install/repositories/ookla/speedtest-cli/script.deb.sh | sudo bash
sudo nano /etc/apt/sources.list.d/ookla_speedtest-cli.list
==> Replace "noble" with "jammy"
sudo apt update
sudo apt-get install speedtest