Before installing DNF5 you should know that your installations with this tool in the fedora distribution may not work correctly
After implementation of dnf5 module install dnf and dnf5 cannot share the same location for storing state of modules, because dnf5 will store additional information about installed profiles (braking change). Modules enabled by DNF5 (dnf5 module enable <module>) will be not seen as enabled in DNF. Module profile installed by DNF5 will be not sees as installed in DNF. DNF will only see installed RPMs.
More details on this official webpage.
You can fix it with the dnf-3 tool if you accidentally modified or deleted the dnf tool.
A simple example is installing Deepin Desktop, which I could only install with DNF-3:
# dnf-3 install @deepin-desktopThe other dnf and dnf5 tools didn't work, I didn't wait to check if it's because of the repos. but it did not bring me the packets from the web and shows me transactions of 0 B.