SUMMARY

Quick tiling (starting with 5.27)  two or more windows on screen edges (half, quarter) forces that their touching borders become magnetic with each and when resizing one, the others are resized in accordance. 

The is user-experience regression as in former version half/quarter-screen-edge quick-tiling was available but when resizing the windows the tiling was removed for this particular window.

STEPS TO REPRODUCE
1. Drag a window to the left screen edge (it becomes half or quarter tiled)
2. Drag a second windows to the right screen edge (it becomes half or quarter tiled)
3. Resized one of the windows 

OBSERVED RESULT
The other one is resized as well.

EXPECTED RESULT
The tiling is deactivated for the resized window and the other one does not change its size, as in previous versions.

I understand the magnetic border is an interesting feature, but I'd like to have a possibility to get the old behavior back.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Debian testing
(available in About System)
KDE Plasma Version: 5.27.10.
KDE Frameworks Version: 5.107.0
Qt Version: 5.15.10

Discussion here: https://discuss.kde.org/t/windows-sticking-together/4339/17