SUMMARY
The "Toggle Grid View" effect does not actually toggle. Hitting the keyboard shortcut twice (with a sensible delay in between) does not deactivate the grid view. This behaviour is different than other toggles such as "Toggle Present Windows (Current Desktop)" wherein if you use the shortcut twice, you're left back in a normal state.

STEPS TO REPRODUCE
1. Hit the "Toggle Grid View" shortcut (Meta+G by default)
2. Hit the "Toggle Grid View" shortcut again


OBSERVED RESULT
You are still in the Grid View mode.

EXPECTED RESULT
You should not be in the Grid View Mode.

SOFTWARE/OS VERSIONS
Operating System: Gentoo Linux 2.17
KDE Plasma Version: 6.3.0
KDE Frameworks Version: 6.10.0
Qt Version: 6.8.1
Kernel Version: 6.6.74-gentoo (64-bit)
Graphics Platform: X11
Processors: 16 × AMD Ryzen 7 2700 Eight-Core Processor
Memory: 62.7 GiB of RAM
Graphics Processor: NVIDIA GeForce RTX 2060 SUPER


ADDITIONAL INFORMATION
Pressing "Esc", "Enter" or a virtual desktop number seems to be the only keyboard-based way to exit Grid View.
"Toggle Overview" behaves similarly, but the difference is that the modifier part of the shortcut (Meta by default) is ignored, and you are placed in the search box, so triggering the shortcut a second time will have you write the shortcut letter in the search box. The Grid View has no such search box.
Interestingly enough, the "Present Windows" mode does have a search box, but you can hit the shortcut twice in a row to exit Present Windows mode.