F-droids official statement from Mastodon:

If you feel that #FDroid downloads are slow, just press ❎ to cancel the download then press Install/Update again so it picks up some other mirror.

There’s no unified “F-Droid server” but several and a dozen or more mirrors.

Each time you try again it will use a different one. Hopefully the next one will have better bandwidth.

/PS: We’ve seen the reports, we will look into it.

https://floss.social/@fdroidorg/115094865087979065