Operating system: Linux Mint Package manager: APT
We are here talking about updating Firefox, which comes pre-installed with the OS.
While other packages go up to 13 MB/s, Firefox downloads remain at a maximum of 500 kB.
Get:1 http://packages.linuxmint.com virginia/upstream amd64 firefox amd64 124.0.2+linuxmint1+virginia [74.3 MB]
Should I switch to different source?
You could try the official deb package: https://support.mozilla.org/en-US/kb/install-firefox-linux#w_install-firefox-deb-package-for-debian-based-distributions
Personally I prefer Firefox’s self updater, i.e just extract the tar.gz and create a desktop file for it. But to each their own.