Yes, disabling /masking WPA service (not uninstall, just disable) fixes the problem and shutdown completed in few seconds…
I can also confirm the issue does not exist in Fenix built Ubuntu mainline, it uses kernel 5.10 however… Manjaro is on 5.12… Maybe it’s something new…
I’m even prepared for any hack script which disables the WPA on shutdown and re enables on boot, but I’m not exactly confident I can do it without breaking anything else.