Unfortunately I cannot freely choose a mirror to download the image from. Is there a solution to this? Does someone has a virus-free direct link not changing mirror to this site?
However it is very unlikely that you have downloaded an ISO containing a virus. Like suggested by @vgaetera it is a false positive. Which operating system are you using? Which version of Firefox?
@alciregi, I found that equally hard to believe, but did not find any option for mirrors to cross-check whether this is a false-positive or not. I am also not too familiar with checking GPGs and was not thinking of it.
Thanks to you for providing me the link to the mirrors. Having now tried it with the “next” server, I did not get this warning. While I have not checked further, Firefox at least thinks that both are different, as in I did not get any virus warning. With the seemingly clean version, I am now able to clean-install my system.
Thanks again and of course also thanks to @vgaetera! I possibly need to get a bit more familiar with the whole GPG checksum verification in the future.
However, for the records, I downloaded the ISO from such mirror, and following the steps to verify it for security and integrity, as documented on https://getfedora.org/en/security, the result is
