I have 13.4 on an external seagate firecuda 500gb on my M1 Mac mini 2020 with 8gb ram and 256gb ssd. I goto software update and it downloads 13.4.1. Then it shows white progress bar and black screen with apple logo and several minutes to finsh installing. And then it boots back to the desktop without asking for password. About this Mac still says 13.4. No 1 at the end. I have downloaded several times and rebooted. Same thing. No 1. Still says 13.4 instead of 13.4.1.