White window on my MacBook M1 startup

Any of the below should be removed as per Developers Instructions 

Open Cleaner one Pro from Trend Micro

Size: 994.66 GB

Free: 83.44 GB

Available: 552.09 GB

Right now, the computer is running low on Empty Space

There is Purgeable Space and there is Empty Space.

Purgeable Space which is Controlled by the Operating System. When the Operating Systems decides the computer needs additional Empty Space, it will move a portion of the Purgeable to Empty space

AFAIK - there is no User Actions to hasten this transition from Purgeable to Empty Space

It can day or longer before this will occur.

Restart in Safe Mode. This will perform a Disk Repair, it will system clear cache files and only load Apple Software, extensions and fonts. The boot up will be slow and can take some time - Normal.

Safe Mode will also eliminate Third Party Software, extensions and drivers from loading. It will only load the Minimum amount of Core Apple Processes to allow the the computer to function at a reduced Level of Performance 

Does the issue present in this mode ?

anding70 wrote:

Thank you for the response. Do you mean starting the Mac in safe mode? I've already done that, and in this mode, the window didn't appear. But in normal reboot, it came back.

It points to some third party interference: log in items, browser extensions, or third party application...

Uninstall all third party apps that are Cleaners/Optimizers/VPN/Anti-Virus

all known to cause issues on the macOS

third-party sync software like:  OneDrive,  GoogleDrive, BackBlaze or DropBox is known to cause some issues...

unplug all non-essential third party peripherals when testing

You can get a good look at your User/System config. and reveal conflicts or issues, you can download/run this trusted utility: https://etrecheck.com  

If you need help interpreting the report you can post it here in its entirety in the "Additional Text" box in the editing toolbar below, in your reply.

anding70 wrote:

Hello everyone, recently, every time I start up (or restart) my MacBook M1, I see a small white window appear for a fraction of a second. To figure out what it was, I had to record a slow-motion video and then search for the frame. The window just says "window" at the top and nothing else. I've attached a screenshot. Does anyone else experience this? I've already tried removing all the programs set to start automatically, but it hasn't changed anything. Does anyone have any suggestions? Thank you.

A SafeBoot Use safe mode on your Mac - Apple Support will sort many anomalies

Out of my respect for my learned colleague @leroydouglas who suggested Etrecheck Application

It maybe best if I observe and not interfere.

The fact that a Disk Cleaner is installed and used on this computer is s telltale sign of what is Disk Cleaner has done to the User Account Folder ( Home Folder )

Safe Mode will also eliminate Third Party Software ( Open Cleaner one Pro ) from loading

As a Start - re-run a new Etrecheck Report and post the new one

Just to make sure all the Bits and Pieces of Open Cleaner one Pro ) have been Removed Totally

Thank you for the new report

This will be a good starting point for @leroydouglas to the being suggesting remedial actions or suggestions

Welcome