Welcome screen every time I startup

Your M4 Mac mini repeatedly displays the “You’ve updated to macOS…” message, requests an Apple Account sign-in, and returns to the Welcome screen at startup. 

These screens would not normally be expected on every startup after an update, so the cause needs further investigation.

First, confirm the installed macOS version under Apple menu >> About This Mac, since your description mentions both 27.0 and 27.0.1. 

Then check System Settings >> General >> Software Update for available updates.

If the issue persists, try starting your Mac in Safe Mode and then restart normally to see whether the behaviour changes. 

Safe Mode is a diagnostic step, not a reset. 

Apple explains the procedure here: Start your Mac in safe mode. ( Do Not Use RESTART ) 

If the problem continues, does the Apple Account sign-in appear before or after you enter your usual Mac login password?

Apple’s macOS startup troubleshooting guide provides additional general guidance.

If the Welcome screens continue in both normal mode and after testing Safe Mode, contact Apple Support for further diagnosis before attempting more disruptive steps, such as reinstalling macOS.

I have encountered this issue previously.

In that instance, completing the outlined procedures from start to finish resolved the recurring “Welcome Screen” at startup. 

Maybe try this:

Backup.

Download the latest GG:

How to download and install macOS - Apple Support

Apply GG installer on top of the old install. Or optionally prepare a bootable USB installer, boot to it and, and apply it:

Create a bootable installer for macOS - Apple Support

Hopefully the welcome screen then comes only once.

I second what Owl-53 has stated. I had a similar issue and until I completed the setup 100% the startup message continued. That means setting up Touch ID, and signing into iCloud, etc..

Before proceeding make sure you have a Backup of your important files

If you have used or are using Time Machine Backup Utility  you maybe able to Restore the Deleted Files 

For future purposes

To truly protect your non replaceable Data

Have a 3-2-1 Rescue Plan in place and always current

3 Backups using 2 methods and 1 off site incase of natural disaster or un-natural disaster.

Each of the above should be done to a Dedicated Single Purposed External Drive 

Below link is intended to augment what TM Backup does 

https://bombich.com

How to schedule a backup

Use the Erase All Content and setting feature

For Apple Silicon computer >> Use Disk Utility to erase a Mac with Apple silicon.

Use the Erase All Content and Settings feature to quickly and securely erase all settings, data, and apps, while maintaining the operating system currently installed.

Effectively, this will put the computer back to its starting point

Set it up again and report back if the current issue returns

All of those things had already been set up. This isn't a new computer. I've done multiple updates on it previously. Even if I skip all the steps it asks me to complete, my computer finally boots up and I'm already logged into my iCloud and accounts that need my Apple ID. I've tried signing in during the boot process and not signing in and it makes no difference.

I am running OS 27.0.1. The "27.0" was the only selection available in the menu to be able to post my question. The "Software Update Complete" sign comes up after I log into my computer. When I click, "Continue" it asks me to sign into my iCloud account. Once I've done that, the "Welcome" screen comes up and says, "Get Started." If I then restart, the same "Software Update Complete" sign comes up. If I hit "set up later" when it asks me to sign into my iCloud account and select, "Skip", the "Welcome" sign comes on and when I hit, "Get Started" I'm already signed into my iCloud account and everything works normally. This is after starting up in Safe mode and running Disk Utility First Aid.