look the systemd script in /usr/lib/systemd/system/fail2ban.service, found:
[Service]
Type=simple
Environment="PYTHONNOUSERSITE=1"
ExecStartPre=/bin/mkdir -p /run/fail2ban
ExecStart=build/bdist.linux-aarch64/wheel/fail2ban-1.1.0.data/scripts/fail2ban-server -xf start
# if should be logged in systemd journal, use following line or set logtarget to sysout in fail2ban.local
# ExecStart=build/bdist.linux-aarch64/wheel/fail2ban-1.1.0.data/scripts/fail2ban-server -xf --logtarget=sysout start
ExecStop=build/bdist.linux-aarch64/wheel/fail2ban-1.1.0.data/scripts/fail2ban-client stop
ExecReload=build/bdist.linux-aarch64/wheel/fail2ban-1.1.0.data/scripts/fail2ban-client reload
so, what is the “build/bdist.linux-aarch64/wheel/fail2ban-1.1.0.data/scripts/” ?
change to /usr/bin , works.