Icons quality bug in dock menu

Please illustrate the issue by posting a screenshot.

Take a screenshot on Mac - Apple Support

See if the problem is present when you boot in safe mode. That process performs some system cleanup and clears caches, and also disables 3rd party extensions that may cause problems.

Start up your Mac in safe mode - Apple Support

If that does not correct the issue, test in a new user account. A newly-created user account will have all settings at default, and if the issue does not occur in that new account then it provides guidance on what may need to be changed to correct the issue.

Add a user or group on Mac - Apple Support

Once the testing is complete, the new account can easily be deleted.

Delete a user or group on Mac – Apple Support

If you have 3rd party ‘protection’ software installed, that may be the problem. That includes:

Cleaners (software claiming to automatically free up space)

Optimizers (software claiming to make your Mac run faster)

Antivirus software

VPN software (unless provided by a school/employer to enable access to internal resources from a remote location)

Such 3rd party system ‘helpers’, ‘cleaners’ and ‘protectors’ do more harm than good. In fact, such products are completely unnecessary for macOS and the only ‘good’ (if you want to call it that) they do is to put money in the developers’ pockets. Cleaners and protectors cause compatibility issues, often after macOS updates. Commercial VPNs claim to hide your browsing activity from websites, and while that may be true those VPN providers just sell your browsing data to others. For the user, all of these types of software offer only harm…and if that is limited to harm to your bank account, then count yourself lucky. If you have installed such software, follow the developer’s instructions to completely uninstall it (note that some developers fail to provide instructions and their software installs can be pervasive, meaning the only way to truly remove it is to erase your Mac, reinstall macOS then restore your user files from a backup).

It might help to download and run EtreCheck, written by a long-time forum member. The free version is fine. Post the full report using the Additional Text button. No personal information is revealed. 

Icons in the Dock look normal (crisp and sharp) for me on macOS 27 Golden Gate (though of course there are a few design changes from Tahoe).

Another quick test: make a new user, log in to that user - same problem with icons or not?

If the test user does not have it, then it is something particular to your regular account.

Did you restart your mac once again? This looks like it could a temporary glitch that might be fixed with a restart.

Also, you may want to try making some changes to the size of icons and see if that makes things ok.

If you use third-party applications for the dock, the icons there are perfectly clear as before. but I don't intend to use this. Most likely I won’t be able to fix this bug from the user settings side, although I haven’t seen anyone have such a problem.

The ones on top do seem to be more "jagged" but on a normal size it does not seem like such a big difference.

I tested this on my Mac by making the Dock on the bottom and the largest it can be, and I CANNOT reproduce the problem - all icons are rendered perfectly fine.

I rebooted my Mac more than once, reset the icon cache, restarted WibdowServer, etc. Nothing helped, I don’t see this problem in others. Scaling is by default; there were no problems on MacOs 26.

Here, for comparison, is how it was and how it became. in safe mode the problem does not disappear, a new user does not change the situation either. There are no third-party software “helpers”

Yes, you can’t repeat it in any way, because you don’t have it. If I increase the size of the dock the problem does not go away.