Why do all Base (noble) mirrors show 0 kB/s in Linux Mint 22.3?

For the Base (noble)

For the Main (Zena)

I've been facing this issue for the past 3-4 weeks: all the mirrors for Base (noble) show a speed of 0 kB/s. There is no such issue when selecting mirrors for Main (Zena). I am attaching the screenshots for both of these.

All updates are working fine, both through the Update Manager and via apt update in the terminal.

I'm using Linux Mint 22.3. What could be causing this issue?