SUMMARY
While using Kile there are happening some weird effects when editing the LaTeX code. Here there are few examples:
- when I scroll the LaTeX code and then select a line to put there the cursor 
it sometimes happens that the cursor goes to another line;
- while scrolling it sometimes happens that a line is duplicated beside the original line;
- when scrolling and then selecting a line it sometimes happens that the hide/view button of the groups of code (from begin(function) to end(function)) traslate towards up.
Each of these bugs are recorded in a video I have attached. 

STEPS TO REPRODUCE
1. Open Kile
2. Try to select a line
3. 

OBSERVED RESULT
It sometimes happens that the cursor doesn't go to the line and column you have selected and some lines are duplicated. 

EXPECTED RESULT
The cursor goes to the line you have selected and while scrolling you don't see duplicated lines.

SOFTWARE/OS VERSIONS
Operating System: Fedora 34
KDE Frameworks Version: 5.82.0
Qt Version: 5.15.2
Kernel Version: 5.12.9-300.fc34.x86_64
OS Type: 64-bit
Graphics Platform: X11
Processors: 8 × Intel® Core™ i7-1065G7 CPU @ 1.30GHz
Memory: 7.5 GiB of RAM
Graphics Processor: Mesa Intel® Iris® Plus Graphics
KDE plasma versione: 5.82.0

ADDITIONAL INFORMATION
See the attachment