Comment 4 for bug 1921696

Same problem here in different architecture:
O.S. Ubuntu 21.04 Beta arm64 (Raspberry Pi 4B 8Gb).

Fails during boot:

# systemctl status systemd-rfkill.service
● systemd-rfkill.service - Load/Save RF Kill Switch Status
     Loaded: loaded (/lib/systemd/system/systemd-rfkill.service; static)
     Active: failed (Result: exit-code) since Sat 2021-04-10 09:19:40 CEST; 8min ago
TriggeredBy: ● systemd-rfkill.socket
       Docs: man:systemd-rfkill.service(8)
    Process: 786 ExecStart=/lib/systemd/systemd-rfkill (code=exited, status=1/FAILURE)
   Main PID: 786 (code=exited, status=1/FAILURE)
      Error: 5 (Error de entrada/salida)

abr 10 09:19:40 fpgrpi systemd[1]: Starting Load/Save RF Kill Switch Status...
abr 10 09:19:40 fpgrpi systemd-rfkill[786]: Read event structure of invalid size.
abr 10 09:19:40 fpgrpi systemd[1]: systemd-rfkill.service: Main process exited, code=exited, status=1/FAILURE
abr 10 09:19:40 fpgrpi systemd[1]: systemd-rfkill.service: Failed with result 'exit-code'.
abr 10 09:19:40 fpgrpi systemd[1]: Failed to start Load/Save RF Kill Switch Status.

But after boot if it's started manually (systemctl start systemd-rfkill.service) it starts without errors.