On macOS 27 Golden Gate, I find that Mission Control and Spaces behave mostly as it did on prior versions of macOS, and as expected based on Apple's information:
View open windows and spaces in Mission Control on Mac – Apple Support
Work in multiple spaces on Mac – Apple Support
There is one difference I see between my two Macs with one on Golden Gate and the other on Tahoe with a window made full screen then a three-finder swipe. On Golden Gate, the Space that is selected is the 'last' one before the full screen window, and that's also the one that's shown occupying most of the screen (top panel, which is a 5K;2K display). On Tahoe, the full screen window is the one that is selected, and the 'first' Space is the one that is shown (bottom panel).
However, clicking on another Space goes to that Space, and there is no 'glitching' when switching Spaces or selecting other apps/windown in Mission Control that I see on Golden Gate.
Have you rebooted your Mac? If not, that's the first step. If that does not help, then 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
Those steps will help to isolate the problem.
If the problem you are seeing remains, then bugs can be reported to Apple here:
Feedback - macOS - Apple
